20．- Goods imported from abroad are ______ those made in China.

　　　 - Yes．Some of the goods made in our country are of high quality.

　　　 A．always as good as　　　　　 　　　　　　　 B．always no better than

　　　 C．not so well as　　　　　　　 　　　　　　 D．not always better than

19．He was busy writing a story, only ______ once in a while to smoke a cigarette.

　　　 A．to stop　　　　　　　　 B．stopping　　　　　　　 C．to have stopped　　 D．having stopped

18．No matter how frequently ______, the works of Shakespeare always attract large audiences.

　 　 A．performed　 　　　　 B．performing 　　　　 C．being performed　 D．to be performed

17．I don’t remember how many years ago ______ people began to grow crops.

　 　 A．it was when　 　 B．it was that　　 　　 C．was it when　　 　 D．was it that

16．You have no idea how she finished the relay race with her foot　 so much.

　 　 A．to wound　 　　　　 B．wound　　　 　　 C．wounded　 　　　　 D．wounding

15．–-Where did you put the car keys?

--Oh, I _______ I put them on the chair because the phone rang as I _______in.

　　　 A．remembered; come　　　　　　　　　　　　　　　 B．remembered; was coming

　　　 C．remember; come　 　　　　　　　　　　　　　　　　 D．remember; was coming

14．The river beyond our school has become clean again as new measures are ______ to prevent it ______ any further.

　 　 A．taken; polluting　　　　　　　　 　　　 B．taking; being polluted

　 　 C．taken; being polluted　　　　　　 　　　 D．taking; to be polluted

13．----What’s happened to George?

　 　----I don’t know．He ________.

　 　　 A．must have got lost　　　　　　　　　　　　　　　 B．may have got lost

　 　　 C．should have got lost　　　　　　　　　　　　　　 D．can’t be lost