11. It is fairly common in Africa for there______ a group of expert musicians surrounded by others who also join in the performances.
A. being B. to be C. be D. is
解析：there be 结构，用在for sb. to do sth结构中
12. ----Now that you like the computer so much. Why not buy it?
---Well, I can’t afford ______computer.
A. that expensive a B. a that expensive C. that an expensive D. an expensive that
解析：that expensive a = so expensive a “that” 为副词
13. He has got himself into a dangerous situation ______ he is likely to lose control over the plan.
A. where B. which C. where D. why
解析：situation, case , point, 等词后常用where引导定语从句 ; occasion 后常用when 引导定语从句。
14. ______, the concert began.
A. The listeners having taken their seats B. Having taken their seats
C. Having taken their places D. Taking their seats
解析：独立主格做状语。主语concert 不可能执行take the seat 这一动作，必须加the listeners 做逻辑主语
15. ---- You shouldn’t have gone there alone last night.
---- But I ______, because Xiao Wang went there, too.
A. didn’t B. had to C. did D. should
解析：表过去的事实。
16. ---- There is a lot of smoke coming out of the teaching-building there.
---- Really? It _____ be a fire, most probably.
A. can B. ought to C. have to D. must
解析：从most probably.可以看出是很可能, must表示一定
17. If you don’t wait _______ the red light, you will be punished by the policeman.
A. at B. under C. for D. on
解析：at 意为“看见”
18. ________ doesn’t seem to have been much difficulty in solving the problem.
A. It B. That C. There D. He
解析：这是There be句型一种比较复杂的表现形式，由下列各句逐步形成：
There is much difficulty in solving the problem.
There seems to be much difficulty in solving the problem.
There seems to have been much difficulty in solving the problem.
There doesn’t seem to have been much difficulty in solving the problem.
E.g. There used to be a big tree in front of the old house.
There happened to be a foreign teacher there.
There is said to be no life on the moon.
There must have been something wrong with the machine.
19. Are the parents who let their child who is ______ walk in the dark alone at night considerate?
A. young enough B. too young to C. not old enough to D. so young
解析：分析句子结构，who is so young 在句为修饰的定语,另有let sb.do sth.
20. If you want to sell your product you must _____ it.
A. advertise B. advertise for C. advertise on D. advertise to
解析：advertise sth. 为……登广告， 登广告宣传…… advertise for sth.(sb.)登广告征求或寻找某物或某人
比较：advertise jobs 登广告招人 advertise for jobs 登广告求职
