выполнить, буду благодарен)

51a.

1 have to

2 had to

3 need

4 have to

5 need

6 must

51b

1 has to buy

2 have to find

3 must to go

4 Do we need to leave

5 must to clean

6 Did you have to pay

45a

1 Bob wasn't able to read until he was six.

2 We are able to see the sea from our window.

3 Not many people are able to drive a bus.

4 We were able to speak to them in English.

5 They weren't able to dance or sing.

6 I didn't able to understand the film.

52a

1 mustn't swim

2 aren't allowed to speak

3 mustn't touch

4 couldn't enter

5 can't use

6 aren't allowed to smoke

53a

1 a

2 f

3 e

4 d

5 b

6 c