The children ..... (play) on the computer for a long time. Tell them to stop.
Jill ..... (swim) in this lake since she was a child.
The students ..... (try) to reduce pollution for years.
How long ..... (you/take care) of this injured cat?
You look tired. ....... (you/work) in the garden all afternoon?
Acid rain ..... (destroy) natural habitats for years
Nick ..... (work) here for over ten years.