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