- 电子工业出版社
- 9787121316623
- 1-1
- 284616
- 46217865-8
- 平塑
- 16开
- 2017年10月
- 493
- 308
- 电子科学与技术
- TM133
- 电子科学与技术(工学/理学)
- 研究生、本科
内容简介
本书包括电路的基本概念与基本定律、电路的等效变换、电路的基本分析方法、电路的基本定理、正弦稳态电路的分析、耦合电感和理想变压器、三相电路、非正弦周期电流电路、动态电路的时域分析、双口网络和非线性电阻电路共11章内容。本书最大的特点是所有的知识点都配有教学视频、电子课件，在线测试等，各章还配有小结视频、综合测试题及测试题讲解视频。扫描书上的二维码就可以观看视频、完成在线测试并实时查看测试结果以及参与交流讨论等。因此，本书不仅适用于传统方法教学，还适用于MOOC教学。本书与国家首批精品在线开放课程《电路分析基础》相配套，在线课程免费对所有高校老师和学生开放，课程链接为：http:///course/detail/30007327。本书可作为本科院校和高职院校电气与电子信息类各专业及其他相近专业的教材，也可用于混合式教学或供相关科技人员参考。
目录
第 1章电路的基本概念与基本定律·························································· 1
1.1电路的组成与电路模型 ············································································ 1
1.1.1 电路的组成及其作用 ········································································· 1
1.1.2 电路模型 ························································································ 2
1.2电路的基本物理量 ·················································································· 3
1.2.1 电流 ······························································································ 3
1.2.2 电压和电位 ····················································································· 5
1.2.3 功率 ······························································································ 7
1.3基尔霍夫定律 ························································································ 8
1.3.1 基尔霍夫电流定律 ············································································ 9
1.3.2 基尔霍夫电压定律 ··········································································· 10
1.4无源元件 ····························································································· 12
1.4.1 电阻元件 ······················································································· 12
1.4.2 电容元件 ······················································································· 14
1.4.3 电感元件 ······················································································· 16
1.5有源元件 ····························································································· 18
1.5.1 独立电源 ······················································································· 18
1.5.2 受控电源 ······················································································· 20
1.6应用实例 ····························································································· 23
1.6.1 电吹风机 ······················································································· 23
1.6.2 汽车油箱油量检测电路 ····································································· 25
本章小结 ··································································································· 26
习题 1 ······································································································· 28
第 2章电路的等效变换 ······································································32
2.1二端网络等效的概念 ·············································································· 32
2.2电阻的等效变换 ···················································································· 33
2.2.1 电阻的串并联等效变换 ····································································· 33
2.2.2 电阻的 Y-△等效变换 ······································································· 35
2.3电源的等效变换 ···················································································· 37
2.3.1实际电源的两种模型及其等效变换 ······················································ 37
2.3.2 理想电源的串并联等效 ····································································· 39
2.4电路的等效分析 ···················································································· 41
2.5无源二端网络的等效电阻 ········································································ 42
2.6应用实例 ····························································································· 43
2.6.1直流电表的设计 ·············································································· 43
2.6.2 惠斯通电桥电路 ·············································································· 45
本章小结 ··································································································· 46
习题 2 ······································································································· 48
第 3章电路的基本分析方法·································································52
3.1支路电流法 ·························································································· 52
3.1.1 两类约束和电路方程 ········································································ 52
3.1.2 支路电流方程的列写 ········································································ 53
3.1.3 含受控源的支路电流方程 ·································································· 54
3.2网孔电流法与回路电流法 ········································································ 55
3.2.1 网孔电流方程的标准形式 ·································································· 55
3.2.2 含电流源的网孔电流方程 ·································································· 56
3.2.3 含受控源的网孔电流方程 ·································································· 57
3.2.4 回路电流法 ···················································································· 58
3.3节点电压法 ·························································································· 58
3.3.1 节点电压方程的标准形式 ·································································· 58
3.3.2 含纯理想电压源支路的节点电压方程 ··················································· 61
3.3.3 含受控源的节点电压方程 ·································································· 63
3.4应用实例 ····························································································· 64
本章小结 ··································································································· 66
习题 3 ······································································································· 66
第 4章电路的基本定理 ······································································70
4.1叠加定理 ····························································································· 70
4.1.1 叠加定理的基本内容 ········································································ 70
4.1.2 应用叠加定理的注意事项 ·································································· 71
4.1.3 线性电路的齐次性与可加性 ······························································· 72
4.2替代定理 ····························································································· 74
4.3等效电源定理 ······················································································· 75
4.3.1 戴维南定理 ···················································································· 75
4.3.2 诺顿定理 ······················································································· 79
4.4昀大功率传输定理 ················································································· 81
4.5特勒根定理和互易定理 ··········································································· 83
4.5.1 特勒根定理 ···················································································· 83
4.5.2 互易定理 ······················································································· 86
4.6应用实例 ——数/模转换器 ······································································· 89
本章小结 ··································································································· 91
习题 4 ······································································································· 92
第 5章正弦稳态电路的分析·································································96
5.1正弦量的基本概念 ················································································· 96
5.1.1 频率与周期 ···················································································· 97
5.1.2 振幅与有效值 ················································································· 97
5.1.3 初相位 ·························································································· 98
5.2正弦量的相量表示法 ············································································ 100
5.2.1 复数及其运算 ··············································································· 100
5.2.2 相量的概念 ·················································································· 102
5.2.3 相量图 ························································································ 103
5.2.4 相量的运算性质 ············································································ 104
5.3两类约束的相量形式 ············································································ 105
5.3.1 基尔霍夫定律的相量形式 ································································ 105
5.3.2 电路元件伏安关系的相量形式 ·························································· 106
5.4无源单口网络的阻抗 ············································································ 110
5.4.1 阻抗的概念 ·················································································· 110
5.4.2 阻抗的串联和并联 ········································································· 112
5.4.3 电路的相量模型 ············································································ 114
5.5正弦稳态电路的相量法分析 ··································································· 115
5.5.1 简单交流电路的分析 ······································································ 115
5.5.2 复杂交流电路的分析 ······································································ 119
5.6正弦交流电路的功率 ············································································ 121
5.6.1 瞬时功率 ····················································································· 121
5.6.2 平均功率和功率因数 ······································································ 122
5.6.3 无功功率 ····················································································· 123
5.6.4 视在功率 ····················································································· 124
5.6.5 复功率 ························································································ 127
5.6.6 电路功率因数的提高 ······································································ 128
5.6.7 正弦交流电路中的最大功率传输 ······················································· 130
5.7电路的频率响应 ·················································································· 132
5.7.1 网络函数和频率特性 ······································································ 132
5.7.2 RC低通滤波电路 ·········································································· 133
5.7.3 RC高通滤波电路 ·········································································· 134
5.8谐振电路 ··························································································· 135
5.8.1 串联谐振 ····················································································· 135
5.8.2 并联谐振 ····················································································· 138
5.9应用实例 ··························································································· 140
5.9.1 日光灯电路 ·················································································· 140
5.9.2 收音机调谐电路 ············································································ 141
5.9.3 按键式电话机 ··············································································· 142
5.9.4 交叉网络 ····················································································· 143
本章小结 ································································································· 144
习题 5 ····································································································· 147
第 6章耦合电感和理想变压器 ·····························································151
6.1耦合电感 ··························································································· 151
6.1.1 互感 ··························································································· 151
6.1.2 耦合电感的伏安关系 ······································································ 152
6.1.3 耦合电感的同名端 ········································································· 153
6.1.4 耦合电感的等效电路模型 ································································ 155
6.2含耦合电感的正弦稳态电路的分析 ·························································· 156
6.2.1 直接列写方程法 ············································································ 156
6.2.2 去耦等效分析法 ············································································ 157
6.3空心变压器························································································ 162
6.4理想变压器 ························································································ 164
6.4.1 理想变压器的基本性质 ··································································· 164
6.4.2 含理想变压器的电路分析 ································································ 166
6.5应用实例 ··························································································· 167
6.5.1 变压器用做隔离装置 ······································································ 167
6.5.2 变压器用做阻抗匹配器 ··································································· 168
本章小结 ································································································· 169
习题 6 ····································································································· 170
第 7章三相电路·············································································174
7.1三相电源 ··························································································· 174
7.1.1 三相电源的产生 ············································································ 174
7.1.2 三相电源的连接 ············································································ 175
7.2对称三相电路 ····················································································· 177
7.2.1 负载 Y形连接 ··············································································· 177
7.2.2 负载△形连接 ··············································································· 179
7.3不对称三相电路·················································································· 181
7.3.1 负载 Y形连接 ··············································································· 181
7.3.2 负载△形连接 ··············································································· 183
7.4三相电路的功率 ·················································································· 184
7.4.1 平均功率 ····················································································· 184
7.4.2 无功功率 ····················································································· 184
7.4.3 视在功率 ····················································································· 185
7.4.4 瞬时功率 ····················································································· 185
7.4.5 三相功率的测量 ············································································ 186
7.5应用实例 ··························································································· 187
7.5.1 相序测定电路 ··············································································· 187
7.5.2 家庭电路 ····················································································· 188
7.5.3 三相电路实例分析 ········································································· 189
本章小结 ································································································· 190
习题 7 ····································································································· 192
第 8章非正弦周期电流电路································································194
8.1非正弦周期信号及其傅里叶级数展开 ······················································· 194
8.1.1 非正弦周期信号 ············································································ 194
8.1.2 非正弦周期信号的傅里叶级数展开 ···················································· 195
8.2非正弦周期信号的有效值和平均功率 ······················································· 196
8.2.1 非正弦周期信号的有效值 ································································ 196
8.2.2 非正弦周期电流电路的平均功率 ······················································· 197
8.3非正弦周期电流电路的分析 ··································································· 199
8.4应用实例 ··························································································· 201
本章小结 ································································································· 203
习题 8 ····································································································· 204
第 9章动态电路的时域分析································································206
9.1动态电路的暂态过程及换路定则 ····························································· 206
9.1.1 动态电路的基本概念 ······································································ 206
9.1.2 换路定则与电路初始值的确定 ·························································· 207
9.2一阶电路的零输入响应 ········································································· 209
9.2.1 一阶 RC电路的零输入响应 ····························································· 209
9.2.2 一阶 RL电路的零输入响应 ······························································ 211
9.3一阶电路的零状态响应 ········································································· 213
9.3.1 一阶 RC电路的零状态响应 ····························································· 213
9.3.2 一阶 RL电路的零状态响应 ······························································ 215
9.4一阶电路的全响应和三要素法 ································································ 217
9.4.1 一阶电路的全响应 ········································································· 217
9.4.2 一阶电路的三要素法 ······································································ 218
9.5阶跃函数和阶跃响应 ············································································ 222
9.5.1 阶跃函数 ····················································································· 222
9.5.2 阶跃响应 ····················································································· 223
9.6冲激函数和冲激响应 ············································································ 225
9.6.1 冲激函数 ····················································································· 225
9.6.2 冲激响应 ····················································································· 226
9.7二阶电路的零输入响应 ········································································· 229
9.7.1 二阶电路方程的建立 ······································································ 230
9.7.2 二阶电路零输入响应的形式 ····························································· 230
9.8应用实例 ··························································································· 236
9.8.1 冰箱延时保护电路 ········································································· 236
9.8.2 积分电路和微分电路 ······································································ 236
9.8.3 方波发生电路 ··············································································· 237
9.8.4 闪光灯电路 ·················································································· 238
本章小结 ································································································· 240
习题 9 ····································································································· 242
第 10章双口网络 ···········································································245
10.1双口网络的基本概念 ·········································································· 245
10.2双口网络的参数方程 ·········································································· 246
10.2.1 阻抗方程与 Z参数 ······································································· 246
10.2.2 导纳方程与 Y参数 ······································································· 249
10.2.3 传输方程与 T参数 ······································································· 251
10.2.4 混合方程与 H参数 ······································································· 252
10.3含双口网络的电路分析 ······································································· 256
10.3.1 含双口网络的电路 ······································································· 256
10.3.2 双口网络的连接 ·········································································· 257
10.4线性双口网络的等效电路 ···································································· 261
10.4.1 互易双口网络的等效电路 ······························································ 261
10.4.2 非互易双口网络的等效电路 ··························································· 263
10.5应用实例 ························································································· 264
10.5.1 放大电路等效模型 ······································································· 264
10.5.2 阻抗匹配电路 ············································································· 265
本章小结 ································································································· 266
习题 10 ··································································································· 268
第 11章非线性电阻电路····································································272
11.1非线性电阻 ······················································································ 272
11.1.1 非线性电阻概述 ·········································································· 272
11.1.2 非线性电阻的静态电阻和动态电阻 ·················································· 273
11.1.3 非线性电阻的串联和并联 ······························································ 274
11.2非线性电阻电路的分析 ······································································· 275
11.2.1 解析法 ······················································································· 275
11.2.2 图解法 ······················································································· 276
11.2.3 分段线性化法 ············································································· 277
11.2.4 小信号分析法 ············································································· 279
11.3应用实例 ························································································· 282
11.3.1 限幅电路 ···················································································· 282
11.3.2 整流电路 ···················································································· 283
本章小结 ································································································· 283
习题 11 ··································································································· 284
习题答案
1.1电路的组成与电路模型 ············································································ 1
1.1.1 电路的组成及其作用 ········································································· 1
1.1.2 电路模型 ························································································ 2
1.2电路的基本物理量 ·················································································· 3
1.2.1 电流 ······························································································ 3
1.2.2 电压和电位 ····················································································· 5
1.2.3 功率 ······························································································ 7
1.3基尔霍夫定律 ························································································ 8
1.3.1 基尔霍夫电流定律 ············································································ 9
1.3.2 基尔霍夫电压定律 ··········································································· 10
1.4无源元件 ····························································································· 12
1.4.1 电阻元件 ······················································································· 12
1.4.2 电容元件 ······················································································· 14
1.4.3 电感元件 ······················································································· 16
1.5有源元件 ····························································································· 18
1.5.1 独立电源 ······················································································· 18
1.5.2 受控电源 ······················································································· 20
1.6应用实例 ····························································································· 23
1.6.1 电吹风机 ······················································································· 23
1.6.2 汽车油箱油量检测电路 ····································································· 25
本章小结 ··································································································· 26
习题 1 ······································································································· 28
第 2章电路的等效变换 ······································································32
2.1二端网络等效的概念 ·············································································· 32
2.2电阻的等效变换 ···················································································· 33
2.2.1 电阻的串并联等效变换 ····································································· 33
2.2.2 电阻的 Y-△等效变换 ······································································· 35
2.3电源的等效变换 ···················································································· 37
2.3.1实际电源的两种模型及其等效变换 ······················································ 37
2.3.2 理想电源的串并联等效 ····································································· 39
2.4电路的等效分析 ···················································································· 41
2.5无源二端网络的等效电阻 ········································································ 42
2.6应用实例 ····························································································· 43
2.6.1直流电表的设计 ·············································································· 43
2.6.2 惠斯通电桥电路 ·············································································· 45
本章小结 ··································································································· 46
习题 2 ······································································································· 48
第 3章电路的基本分析方法·································································52
3.1支路电流法 ·························································································· 52
3.1.1 两类约束和电路方程 ········································································ 52
3.1.2 支路电流方程的列写 ········································································ 53
3.1.3 含受控源的支路电流方程 ·································································· 54
3.2网孔电流法与回路电流法 ········································································ 55
3.2.1 网孔电流方程的标准形式 ·································································· 55
3.2.2 含电流源的网孔电流方程 ·································································· 56
3.2.3 含受控源的网孔电流方程 ·································································· 57
3.2.4 回路电流法 ···················································································· 58
3.3节点电压法 ·························································································· 58
3.3.1 节点电压方程的标准形式 ·································································· 58
3.3.2 含纯理想电压源支路的节点电压方程 ··················································· 61
3.3.3 含受控源的节点电压方程 ·································································· 63
3.4应用实例 ····························································································· 64
本章小结 ··································································································· 66
习题 3 ······································································································· 66
第 4章电路的基本定理 ······································································70
4.1叠加定理 ····························································································· 70
4.1.1 叠加定理的基本内容 ········································································ 70
4.1.2 应用叠加定理的注意事项 ·································································· 71
4.1.3 线性电路的齐次性与可加性 ······························································· 72
4.2替代定理 ····························································································· 74
4.3等效电源定理 ······················································································· 75
4.3.1 戴维南定理 ···················································································· 75
4.3.2 诺顿定理 ······················································································· 79
4.4昀大功率传输定理 ················································································· 81
4.5特勒根定理和互易定理 ··········································································· 83
4.5.1 特勒根定理 ···················································································· 83
4.5.2 互易定理 ······················································································· 86
4.6应用实例 ——数/模转换器 ······································································· 89
本章小结 ··································································································· 91
习题 4 ······································································································· 92
第 5章正弦稳态电路的分析·································································96
5.1正弦量的基本概念 ················································································· 96
5.1.1 频率与周期 ···················································································· 97
5.1.2 振幅与有效值 ················································································· 97
5.1.3 初相位 ·························································································· 98
5.2正弦量的相量表示法 ············································································ 100
5.2.1 复数及其运算 ··············································································· 100
5.2.2 相量的概念 ·················································································· 102
5.2.3 相量图 ························································································ 103
5.2.4 相量的运算性质 ············································································ 104
5.3两类约束的相量形式 ············································································ 105
5.3.1 基尔霍夫定律的相量形式 ································································ 105
5.3.2 电路元件伏安关系的相量形式 ·························································· 106
5.4无源单口网络的阻抗 ············································································ 110
5.4.1 阻抗的概念 ·················································································· 110
5.4.2 阻抗的串联和并联 ········································································· 112
5.4.3 电路的相量模型 ············································································ 114
5.5正弦稳态电路的相量法分析 ··································································· 115
5.5.1 简单交流电路的分析 ······································································ 115
5.5.2 复杂交流电路的分析 ······································································ 119
5.6正弦交流电路的功率 ············································································ 121
5.6.1 瞬时功率 ····················································································· 121
5.6.2 平均功率和功率因数 ······································································ 122
5.6.3 无功功率 ····················································································· 123
5.6.4 视在功率 ····················································································· 124
5.6.5 复功率 ························································································ 127
5.6.6 电路功率因数的提高 ······································································ 128
5.6.7 正弦交流电路中的最大功率传输 ······················································· 130
5.7电路的频率响应 ·················································································· 132
5.7.1 网络函数和频率特性 ······································································ 132
5.7.2 RC低通滤波电路 ·········································································· 133
5.7.3 RC高通滤波电路 ·········································································· 134
5.8谐振电路 ··························································································· 135
5.8.1 串联谐振 ····················································································· 135
5.8.2 并联谐振 ····················································································· 138
5.9应用实例 ··························································································· 140
5.9.1 日光灯电路 ·················································································· 140
5.9.2 收音机调谐电路 ············································································ 141
5.9.3 按键式电话机 ··············································································· 142
5.9.4 交叉网络 ····················································································· 143
本章小结 ································································································· 144
习题 5 ····································································································· 147
第 6章耦合电感和理想变压器 ·····························································151
6.1耦合电感 ··························································································· 151
6.1.1 互感 ··························································································· 151
6.1.2 耦合电感的伏安关系 ······································································ 152
6.1.3 耦合电感的同名端 ········································································· 153
6.1.4 耦合电感的等效电路模型 ································································ 155
6.2含耦合电感的正弦稳态电路的分析 ·························································· 156
6.2.1 直接列写方程法 ············································································ 156
6.2.2 去耦等效分析法 ············································································ 157
6.3空心变压器························································································ 162
6.4理想变压器 ························································································ 164
6.4.1 理想变压器的基本性质 ··································································· 164
6.4.2 含理想变压器的电路分析 ································································ 166
6.5应用实例 ··························································································· 167
6.5.1 变压器用做隔离装置 ······································································ 167
6.5.2 变压器用做阻抗匹配器 ··································································· 168
本章小结 ································································································· 169
习题 6 ····································································································· 170
第 7章三相电路·············································································174
7.1三相电源 ··························································································· 174
7.1.1 三相电源的产生 ············································································ 174
7.1.2 三相电源的连接 ············································································ 175
7.2对称三相电路 ····················································································· 177
7.2.1 负载 Y形连接 ··············································································· 177
7.2.2 负载△形连接 ··············································································· 179
7.3不对称三相电路·················································································· 181
7.3.1 负载 Y形连接 ··············································································· 181
7.3.2 负载△形连接 ··············································································· 183
7.4三相电路的功率 ·················································································· 184
7.4.1 平均功率 ····················································································· 184
7.4.2 无功功率 ····················································································· 184
7.4.3 视在功率 ····················································································· 185
7.4.4 瞬时功率 ····················································································· 185
7.4.5 三相功率的测量 ············································································ 186
7.5应用实例 ··························································································· 187
7.5.1 相序测定电路 ··············································································· 187
7.5.2 家庭电路 ····················································································· 188
7.5.3 三相电路实例分析 ········································································· 189
本章小结 ································································································· 190
习题 7 ····································································································· 192
第 8章非正弦周期电流电路································································194
8.1非正弦周期信号及其傅里叶级数展开 ······················································· 194
8.1.1 非正弦周期信号 ············································································ 194
8.1.2 非正弦周期信号的傅里叶级数展开 ···················································· 195
8.2非正弦周期信号的有效值和平均功率 ······················································· 196
8.2.1 非正弦周期信号的有效值 ································································ 196
8.2.2 非正弦周期电流电路的平均功率 ······················································· 197
8.3非正弦周期电流电路的分析 ··································································· 199
8.4应用实例 ··························································································· 201
本章小结 ································································································· 203
习题 8 ····································································································· 204
第 9章动态电路的时域分析································································206
9.1动态电路的暂态过程及换路定则 ····························································· 206
9.1.1 动态电路的基本概念 ······································································ 206
9.1.2 换路定则与电路初始值的确定 ·························································· 207
9.2一阶电路的零输入响应 ········································································· 209
9.2.1 一阶 RC电路的零输入响应 ····························································· 209
9.2.2 一阶 RL电路的零输入响应 ······························································ 211
9.3一阶电路的零状态响应 ········································································· 213
9.3.1 一阶 RC电路的零状态响应 ····························································· 213
9.3.2 一阶 RL电路的零状态响应 ······························································ 215
9.4一阶电路的全响应和三要素法 ································································ 217
9.4.1 一阶电路的全响应 ········································································· 217
9.4.2 一阶电路的三要素法 ······································································ 218
9.5阶跃函数和阶跃响应 ············································································ 222
9.5.1 阶跃函数 ····················································································· 222
9.5.2 阶跃响应 ····················································································· 223
9.6冲激函数和冲激响应 ············································································ 225
9.6.1 冲激函数 ····················································································· 225
9.6.2 冲激响应 ····················································································· 226
9.7二阶电路的零输入响应 ········································································· 229
9.7.1 二阶电路方程的建立 ······································································ 230
9.7.2 二阶电路零输入响应的形式 ····························································· 230
9.8应用实例 ··························································································· 236
9.8.1 冰箱延时保护电路 ········································································· 236
9.8.2 积分电路和微分电路 ······································································ 236
9.8.3 方波发生电路 ··············································································· 237
9.8.4 闪光灯电路 ·················································································· 238
本章小结 ································································································· 240
习题 9 ····································································································· 242
第 10章双口网络 ···········································································245
10.1双口网络的基本概念 ·········································································· 245
10.2双口网络的参数方程 ·········································································· 246
10.2.1 阻抗方程与 Z参数 ······································································· 246
10.2.2 导纳方程与 Y参数 ······································································· 249
10.2.3 传输方程与 T参数 ······································································· 251
10.2.4 混合方程与 H参数 ······································································· 252
10.3含双口网络的电路分析 ······································································· 256
10.3.1 含双口网络的电路 ······································································· 256
10.3.2 双口网络的连接 ·········································································· 257
10.4线性双口网络的等效电路 ···································································· 261
10.4.1 互易双口网络的等效电路 ······························································ 261
10.4.2 非互易双口网络的等效电路 ··························································· 263
10.5应用实例 ························································································· 264
10.5.1 放大电路等效模型 ······································································· 264
10.5.2 阻抗匹配电路 ············································································· 265
本章小结 ································································································· 266
习题 10 ··································································································· 268
第 11章非线性电阻电路····································································272
11.1非线性电阻 ······················································································ 272
11.1.1 非线性电阻概述 ·········································································· 272
11.1.2 非线性电阻的静态电阻和动态电阻 ·················································· 273
11.1.3 非线性电阻的串联和并联 ······························································ 274
11.2非线性电阻电路的分析 ······································································· 275
11.2.1 解析法 ······················································································· 275
11.2.2 图解法 ······················································································· 276
11.2.3 分段线性化法 ············································································· 277
11.2.4 小信号分析法 ············································································· 279
11.3应用实例 ························································································· 282
11.3.1 限幅电路 ···················································································· 282
11.3.2 整流电路 ···················································································· 283
本章小结 ································································································· 283
习题 11 ··································································································· 284
习题答案
