I would appreciate __________ back this afternoon.
---What’s wrong with him? He is so sad.---He was ____ at not being invited to the party.
____ number of students were absent from the meeting and ____ number of them is only about fifty .
As we all know, parents are concerned _____ their children’s study, because it is concerned ____ their future .
So far, he ______ in remembering 2,000 English words.
-----_______in your city now?-----Very hot at noon but very cool at night.