Hurry up, or you ______ catch the train. 

—Is John coming by train.—He should，but he ________ not.He likes driving his car.

If the government takes measures to enrich senior citizens’ social and spiritual life, it ____ help develop a truly harmonious society.

In ancient times, dogs were mainly ______helping people hunt( 打猎) .Now they are more useful-they can help the blinds, search for the bad eggs,...

--Who’s singing in the next room? Is it Lucy?---It       be her. She has gone to New York.