Rewrite each of sentences so that the meaning stays the same

!.rewrite each of sentences so that the meaning stays the same 
1. we have learnt english for 4 years
> we started.......
2.ly's father started to give up smoking last year
> ly's father has.....
3.the editor hasn't written to mai for a month
>the editor last.......
4.how long have you learnt spanish?
>how long ago......
5they finished their exercises on time yesterday
>their exercises.......