21
[答案]:对
[解析]:参见教材P216
22
[答案]:对
[解析]:参见教材P218
23
[答案]:错
[解析]:参见教材P218
24
[答案]:对
[解析]:参见教材P220
25
[答案]:对
[解析]:参见教材P220
26
[答案]:错
[解析]:参见教材P221
27
[答案]:对
[解析]:参见教材P221
28
[答案]:错
[解析]:参见教材P221
29
[答案]:对
[解析]:参见教材P222
30
[答案]:对
[解析]:参见教材P223
31
[答案]:对
[解析]:参见教材P223
32
[答案]:对
[解析]:参见教材P223
33
[答案]:错
[解析]:参见教材P224
34
[答案]:错
[解析]:参见教材P224
35
[答案]:对
[解析]:参见教材P231
36
[答案]:错
[解析]:参见教材P225
37
[答案]:对
[解析]:参见教材P225
38
[答案]:对
[解析]:参见教材P225
39
[答案]:错
[解析]:参见教材P226
40
[答案]:对
[解析]:参见教材P226
41
[答案]:对
[解析]:参见教材P233
42
[答案]:错
[解析]:参见教材P234
43
[答案]:错
[解析]:参见教材P235
44
[答案]:对
[解析]:参见教材P235
45
[答案]:对
[解析]:参见教材P209
46
[答案]:错
[解析]:参见教材P214
47
[答案]:错
[解析]:参见教材P217
48
[答案]:对
[解析]:参见教材P223