GRAMMAR ANSWER KEY. PAGE 50 of the S.B and PAGE 129

GRAMMAR 
EXERCISE 5
1. wasn't
2. had had
3. not to arrive
4. had been wandering
5. hasn't been driving
6. just taken off
7. had...got on
8. will be travelling

EXERCISE 6
1. mustn't park
2. did...have to check out
3. shouldn't have cheated
4. do...need to leave
5. might have...landed
6. couldn't go
7. weren't able to buy
8. would have taken

EXERCISE 7
1. Besides
2. because of
3. for this reason
4. all of a sudden
5. as soon as
6. during

GRAMMAR 
PAGE 129
Exercise 1
1. ought to
2. couldn't
3. must
4. can't
5. will... be able to
6. might
7.needn't

Exercise 2
1. should have
2. would have
3. couldn't have
4. might have
5. shouldn't have
6. could have
7. must have

Exercise 3
1. can drive
2. should visit
3. could they have already reached
4. oudht to have listened
5. may not leave
6. would have had
7. shouldn't have opened
8. mustn't park