一、
1. A
2. D
3. B
4. D
5. C
6. D
7. A
8. B
9. B
10.B
11.D
12.A
13.D
14.B
15.D

二、
1. needn't   can
2. must
3. can't
4. can't
5. can
6. must
7. can't
8. must
9. have to
10. needn't

三、
1. Yes, I can.
2. What can  do
3. I can't
4. Yes, you must
5. had to
6. What do  have to
7. you needn't
8. Does  have to
9. Must I finish the work today?
10.You don't have to go to the meeting.

四、
1. plays —— play
2. has to —— have to
3. don't have to —— mustn't
4. have to —— has to
5. mustn't —— needn't

一、
1. A
2. D
3. B
4. D
5. C
6. D
7. A
8. B
9. B
10.B
11.D
12.A
13.D
14.B
15.D

二、
1. needn't   can
2. must
3. can't
4. can't
5. can
6. must
7. can't
8. must
9. have to
10. needn't

三、
1. Yes, I can.
2. What can  do
3. I can't
4. Yes, you must
5. had to
6. What do  have to
7. you needn't
8. Does  have to
9. Must I finish the work today?
10.You don't have to go to the meeting.

四、
1. plays —— play
2. has to —— have to
3. don't have to —— mustn't
4. have to —— has to
5. mustn't —— needn't