6. I’m old enough not to let my troubles to interfere with A B C D
my work. (2003年)
7. The ability _______ is very important for any speaker. (1999年)
A. to hear clearly
B. to be clearly heard
C. to hearing clearly
D. to being clearly heard
8. Judging from his manners at the party, he doesn’t seem ______ much education. (1997年)
A. to receive
B. to be receiving
C. to have received
D. to have been received
9. Some cities have passed laws that allow coal and oil ______ only if their sulfur硫黄 content is low. (2005年)
A. burning
B. to burn
C. being burned
D. to be burned
6. I’m old enough not to let my troubles to interfere with my work. (2003年)
解析：答案选C。let是使役动词，其后接不定式时要省略小品词to。类似的使役动词还有make, have。
7. The ability _______ is very important for any speaker. (1999年)
A. to hear clearly
B. to be clearly heard
C. to hearing clearly
D. to being clearly heard
解析：答案选B。ability后接动词不定式。本题意是指演说者被听见的能力。
8. Judging from his manners at the party, he doesn’t seem ______ much education. (1997年)
A. to receive
B. to be receiving
C. to have received
D. to have been received
解析：答案选C。动词receive的动作发生在谓语动词seem之前，所以要用不定式的完成时。句子主语he和动词receive不存在被动关系，因此不用被动。
9. Some cities have passed laws that allow coal and oil ______ only if their sulfur硫黄 content is low. (2005年)
A. burning
B. to burn
C. being burned
D. to be burned
解析：答案选D。 “allow+宾语+不定式”是固定用法。本句中不定式动词burn和宾语coal and oil是被动关系，所以要用不定式的被动式。
