Must I turn off the gas after cooking? —Of course, you can never be ____careful with that．

What does “three quarters” mean, Li Ping? —I see. It means __________.

Why does Sally look so unhappy?—It’s a bad morning for her. When she got off the bus, sheshe had left her purse on it.

Paul learns English ________. He often goes to the English Corner at weekends.

Taking a walk after supper is really a ____ way. –____. It keeps us healthy, too.