20.-Would you like some tea, please ?　 -Yes, I prefer tea 　　　sugar.

A. to 　　 B. for 　　 C. than

19. In his free time, he often teaches me how ________.

A. swim　　　 B. swimming　　 C. to swim

18. -Here is a piece of paper for you !

　-Oh，thanks．It’s 　　 　for me to write a long letter on．

A big enough　 B enough large　 C small enough

17. The trees must _______three times a week.

A. water　　　　 B. watering　　　　 C. be watered　　

16. Children need to 　　　　　after well.

A. be look　　　 B. be looked　　　 C. are looking

15. They are made ______ for 14 hours a day.

A. work　　　　　 B. to work　　 C. worked

14. The boy was seen ______on the sports ground.

A. to play　　　　 B. play　　　 C. to playing

13. Look around while ______ the street.

A. cross　　　　　 B. crossing　 C. crossed　

12. Everyone knows Thomas Edison ________a lot of useful inventions.

A. invents　　　　 B. invented　　　 C. discovers

11. About 5000 cars ________ in the factory last month.

A. have produced　 B. were produced　 C. was produced