IV

1. Listen! I think someone is knocking at the door. 

2. Up to the present, we have been writing almost every lesson in the book. 

3. The earth circles the sun once every 365 days.

4. The farmers are working in the field at the moment. 

5. How many times have you seen him since he went to Edinburgh?

6. Rivers usually flow to the sea. 

7. Look! The boy is crying. 

8. Do you know that man who is smoking there? 

9. Mrs.Green always goes to work by bus. 

10. We are from French. We have been there for 20 years. 

11. That house belongs to Mr.Green. 

12. Mai has lost her dictionary. 

13. I am sorry. I forgot that girl's name already. 

14. I have been waiting for the manager for 2 hours. 

15. Have you ever seen a lion?

V

1. I haven't seen her before.

2. I saw her last year.

3. Tom has never been in Hanoi.

4. I have read the novel written by Jack London several times before.

5. What did you do yesterday?

6. Did you watch TV last night?

7. She was born in 1980.

8. He has written a book since last year.

9. Mr.Green has taught English in this school since he graduated from the university in 1986.

10. How long have you learned English?

11. I was invited to her party last night.

12. My car was repaired yesterday.

IV)

1 . think/is knocking

2 . have written

3 . circles

4 . are working

5 . have you seen

6 . flow

7 . is crying

8 . smoking

9 . goes

10  are/have been

11 . belongs

12 . lost

13 . am/have forgotten

14 .  have been waiting

15 . Have you ever seen

V)

1 . have seen

2 . saw

3 . has never been

4 . have read

5 . did you do

6 . Did you watch

7 . was

8 . wrote

9 . has taught/graduated

10 . have you learnt