Why not take up some outdoor sports to relax ______ office work? It will also help keep you healthy

How the big forest fire has remains to be a mystery.

It was obviously that the man ______ driving on the free way for almost an hour when he ______ that he must come back

Would you mind _______ in the classroom—Sorry, I won’t do that again.

At school, some students are active, ______ some are shy, yet they can be good friends with one another.