Ex3:
1. have
2. not get
3. have
4. can
Ex4
1. have just decided
2. has come
3. has been
4. have you ever been
5. has Lan done
6. have you ever eaten
7. haven't worked
8. have gone
9. hasn't played
10. haven't had
11. haven't gone
12. have been
III.
1. Because Mary was sick, she couldn't go to school.
2. I haven't met him for 3 years.
3. Lan finished her homework, so she went out.
4. He likes doing morning exercise.
5. We started learning English 3 years ago
