1.How long is it since you saw Tom?
When did you see Tom ?
2. He can't pass the examination.
He wishes  passed the examination.
3. We can't go out because of heavy rain.
They wish they could go out
4. They often go to Vung Tau at the weekends.
They used to go to Vung tau at the weekends
5. How long have you learnt French?
How long ago you have learnt French?
6. My father started to give up smoking last year.
My father have given up smoking for year
7. They have worked in that factory since 2001.
They started to work in that factory in 2001
8. I haven't seen her for a long time.
I didn't see her in a long time