20. - Have you played baseball before? We need one more player.

- ______. But I believe it will be fun to learn baseball.

A. Sometimes　 　 B. Not really　 　　 C. Never mind　 　　　　 D. That’s cool

19. -Why does the Lake smell terrible?

- Because large quantities of water　　　 .

　 A. have polluted　　　 　　　　B. is being polluted　　

C. have been polluted　 　　　　D. has been polluted