1. It has started raining an hour ago `⇒` bỏ has

2. I knew Hoa for some months. `⇒` has known

3. We didn’t see Nga since Monday.`⇒` haven't seen

4. Lan was in the USA for 2 years.`⇒ ` has been

5. I have gone to bed at 10 o’ clock last night `⇒` went

6.They moved to London for 2003.`⇒` in

7. How long have you learn English ?`⇒` learned

8. Peter was ill for a week.`⇒` has been 

1. raining-->rain

2. knew ----> have known

3. Didn't see ----> haven't seen

4. Was -> has been

5. have gone ---> went

6. for ---> in

7. learn -> learned

8. was -> has been