Question

Choose the best alternatives.
1) I can't / don't have to go out. I`m too busy.
2)We don't have to / can't catch a taxi. ill drive.
3)I have to \ can go into the army for a year. I don't have a choice.
4)You shouldn't \ don't have to smoke during meals - it's annoying.
5)I should/ have to do more exercise. Im putting on weight.
6)You can / should see the doctor at 5pm on Thursday. That's the earliest time she is free.

Answer 1

1 I can't go out 2 We don't have to 3 I have to go 4 You shouldn't smoke 5 I have to do (хотя, в принципе, should тоже подходит, как совет самому себе, мне следует)
 6 You can see

Answer 2

1) I can't go out. I`m too busy. 
2) We don't have to catch a taxi. I'll drive. 
3) I have to go into the army for a year. I don't have a choice.
4) You shouldn't  smoke during meals - it's annoying.
5) I have to do more exercise. I'm putting on weight. 
6) You can see the doctor at 5pm on Thursday. That's the earliest time she is free.