1. The distance from my house to school is about 2 km (It)
>It's about two kilometers from my house to school.
2. There did not use to be many cars on the roads before.(used)
>Now there are more cars on the road than before.
3 Don't drive too fast or you ll have an accident(if)
>If you drive too fast,you will have an accident.
4 Is it possible to go to Sa pa by motorbike?(Can)
>Can we go to Sa pa by motorbike?