Beijing is a nice city because more and more trees _______ every spring.

It’s very cold these days. Sometimes the temperature falls ________ zero.

Although the children _______ in age _______ seven to thirteen, they have a lot in common.

The state of illness is complicated．We need an experienced doctor．—Whom would you like to have____

Did they have a good time at the party?—Judging by their smiles, they _________ have enjoyed themselves.