20. --______! We’re late for our history lesson!

　 --Oh, god! We’ll have to continue another time.

　 A. Take it easy　　 B. Look at the time　　 C. go on, please　　 D. Never mind

19. I send you 100 dollars today, the rest_____ in a year.

　 A. follows　　　　 B. followed　　　 C. to follow　　　　 D. being followed

18. –Now that you like the portable personal computer so much, why not buy one? It is of great use to your work.

　 --Well, I can’t afford_____ computer at present.

　 A. that expensive a　 B. a such cheap　 C. that an expensive　 D. so cheap

17. In my opinion, our discussion should______ on how to prevent the disease from spreading.

　 A. depend　　　　 B. rely　　　　　　 C. base　　　　　 D. center