21
[答案]:对
[解析]:参见教材P257
22
[答案]:错
[解析]:参见教材P258
23
[答案]:错
[解析]:参见教材P260
24
[答案]:对
[解析]:参见教材P260
25
[答案]:对
[解析]:参见教材P261
26
[答案]:错
[解析]:参见教材P261
27
[答案]:对
[解析]:参见教材P261
28
[答案]:对
[解析]:参见教材P262
29
[答案]:错
[解析]:参见教材P263
30
[答案]:对
[解析]:参见教材P264
31
[答案]:对
[解析]:参见教材P266
32
[答案]:错
[解析]:参见教材P266
33
[答案]:对
[解析]:参见教材P267
34
[答案]:对
[解析]:参见教材P268
35
[答案]:对
[解析]:参见教材P268
36
[答案]:错
[解析]:参见教材P268
37
[答案]:错
[解析]:参见教材P242
38
[答案]:对
[解析]:参见教材P245
39
[答案]:错
[解析]:参见教材P246
40
[答案]:错
[解析]:参见教材P247
41
[答案]:对
[解析]:参见教材P253
42
[答案]:对
[解析]:参见教材P267
43
[答案]:对
[解析]:参见教材P264
44
[答案]:对
[解析]:参见教材P253
45
[答案]:错
[解析]:参见教材P257