---Have you seen Mr. King these days?---No, he together with his members, ______ Shanghai for an international meeting. He’ll come back in three days.
You know the boy is ____ playing the piano.
We should play a part in ______ the earth.
The two students practice spoken English______ joining the English club.
You can’t get good grades______ you study hard.
-I can’t decide______. – You mean the red one or the blue one?