Activity 1:
1. cleaned
2. have collected
3. collected
4. has flown - went
5. Have you ever seen - saw
6. he has ever met
7. visited
8. has visited
9. did - write
10. has - written
Activity 2:
1. b
2. b
3. c
4. a
5. c
6. b
Activity 3:
1. I have known her for a long time
2. They have bought a new house since April
3. My family has been here since Christmas
4. We haven't seen each other for 10 years
5. How long have you ever visited Ha Long Bay?
6. I have written a letter for 2 hours
