7. B

很明显答语在结构上缺少主语。To do 与-ing都可充当主语，但 to do充当主语多表示某一具体的动作，且多表将来。故选B。

6. A

此题可采用减元法。 George thought of 是way 的定语从句，可以去掉，则该句变为What is the way_____ enough money to buy the house？way的定语可用to do或of doing。故选A。

5. C

介词from后应用动词的-ing形式，且settle与problem之间存在着被动关系，故选C。

4. B

此题极易受enjoy后接动词-ing形式的干扰，从而错选A或C。其实，enjoy的宾语是which，即在going abroad与staying at home作出选择；to spend your holiday是作目的状语的。故选B。

3. A

由题意知，农田逐步消失，故应用is getting lost，表示渐进的过程；consider作考虑讲时，后应接动词的-ing形式或带有疑问词的不定式结构。故选A。

2. D

of为介词，后应用-ing形式，且此处是there be结构。故选D。

1. C

warn这一动作发生在主句动作had to go之前，应用-ing的完成形式，且与主句的主语存在着被动关系；a friend与follow之间是主动关系。故选C。

30. ____ at a college or university in the USA, Chinese and other international students must demonstrate a strong ability in spoken and written English.

　 A. Having been accepted　　　 B. To be accepted　　 C. Being accepted　　　　　 D. Accepted

[答案与解析]

29. With a lot of difficult problems ____, the manager felt worried all the time.

　 A. settled　　　　 B. to be settled　　　　 C. settling　　　　 D. to settle

28. As we all know, it was _____ that resulted in the terrible car accident.

　 A. because of her carelessness　　　　　　　　　　　 B. her being careless

　 C. because she was careless　　　　　　　　　　　　　 D. she was so careless