4. Not only is food production important but also taking

　　 care of the environment.

3. To make as much use of the land as possible, two or

　 more crops are planted each year where possible.

2. It is on this arable land that the farmers produce food

　 for the whole population of China.

1. What do you think causes these changes?

8. Children at the beginning of this century ____ a lot and ____ themselves greatly even without television.

A. used to read; enjoying　　 B. used to read; enjoyed

C. were used to reading; enjoy

D. were used to read; enjoying

[解析]选B　 前后时态要保持一致。

7. -- There is something wrong with my bike.

-- It doesn't matter. I ____ lend you mine.

A. am to　 B. am going to　 C. was going to　 D. will

[解析]选D be to表示按计划安排将来的动作，be going to 表示最近打算做某事，will 在此是情态动词，表示“意志；意愿”。如：I will tell you all about it.

6. He made a mistake, but then he corrected the situation ____ it got worse.

A. until　　 B. when 　　C. before　　 D. as

[解析]选C意思是“在事情还未变得更糟之前及

时纠正错误”。

5. John, who is considered ____ a warm-hearted man, is considering ____ his neighbor out of trouble.

A. to be; to help　　 B. to be; helping

C. being; to help　　 D. being; helping

[解析]选B be considered to be “被认为是……”；consider doing “考虑做某事”。

4. -- Excuse me, what time is it now?

　　 -- Sorry, my watch ____. It ____ at the shop.

　　 A. isn't working; is being repaired

　　 B. doesn't work; is being repaired

　　 C. isn't working; is repaired

　　 D. doesn't work; is repaired

[解析]选B doesn't work说明“手表不工作”的状态，而不只是现在才坏了。后句意为“手表正在商店里修理”，故应用is being repaired。

3. -- When are you leaving? 　-- My plane ____ at 10:45.

A. takes off　 　　　　　B. took off

　　 C. is about to take off　 　D. will take off

[解析]选A飞机是按时刻表运行的。