Never form the habit of smoking because it ______ human beings.

You’d better practice more and play better if you wantto make a good ______ on the audience at the concerts.

The air in Beijing is gettingmuch ______ now than a few years ago.

doyou know so much about the UFO?—I usually get the information by surfing theInternet.

Our English teacher is ________us. We all like her.