ex 1: 

1. D

2. A

3.D

4.B

5.B

6.B

7. C

8. D

9. C

10. C

 ex 2:

1. cutted -> cut

2. working -> worked

3. haven't -> hasn't

4.  eat -> been eaten

5. hasn't -> haven't

6. since -> for

7. since -> for

8. for -> since

 ex 3:

1. hasn't played

2. have studied

3. has stayed

4. have ever read

5. haven't invited

 ex 4: 

1. She started to live in Hanoi 2 years ago. (for)

She has lived in Hanoi for 2 years

2. He began to studyEnglish when he was young. (since)

He has studied English since he was young

3. I have never eaten this kind of food before. (This is)

This is the first time I have eaten this kind of food

4. I have never seen such a beautiful girl before. (She is)

She is the most beautiful girl I have seen

5. This is the best novel I have ever read. (before)

I have never read such a good novel like this one before.

I have never read a better novel than this one before.

ex 6:

1. We/ not eat/ out/ since/ mom’s birthday.

⇒We haven't eaten out since our mom's birthday

2. How/ long/ you/ live/ here?

⇒How long have you lived here?

3. You/ ever/ been/ Russia?

⇒Have you ever been to Russia?

4. She/ not/ meet/ kids/ since Christmas.

⇒She hasn't met any kids since Christmas

5. They/ repair/ lamps/ yet?

⇒Have they repaired the lamps yet?