【2013山东济南】It was time for class. Mr. King asked all the children ___________ down quietly.
—People have realized how important the environment is, but still trees ____in the world every year.— We must do something to stop it.
Do you know _____?
There is _____ knocking at the door. Go and see who it is.
—What was your hometown like five years ago?—It _____ very old and dirty.
I won’t take part in the party _____ Joe invites me..