Упражнение1
1) must
2) must
3)mustn't
4) mustn't
Упражнение2
1)have known
2) went
3)have changed
4) change
5)have built
6)has never eaten
7)have met
8)have known
Упражнение3
0) well
1)stomachache
2)dentist
3)a cold
4)put a warm compress
5)vet
