18. The population of this city, forty percent of which ____

18. The population of this city, forty percent of which ________, ________ 15％ in the last three years.
A. are Germans; has risenB. are German; has fallen try
C. is Germans; have increased toD. is Germans; has been reduced try
19. It was about 600 years ago ________ the first clock with a face and an hour hand was made.
A. thatB. until C. before D. when
20. It was 1969 ________ two Americans got to the moon by space ship.
A. whichB. whenC. thatD. as
21. He is the only man ________ for the position.
A. likelyB. possibleC. probably D. possibly
22. When ________ about his plan, he said he hadn’t made it yet.
A. was askedB. askedC. was askingD. asking
23. If you ________ to see Kate, what would you tell him?
A. areB. will beC. mustD. were
24. She asked the pupil ________ still, but they kept ________ out of class.
A. to sit; to moveB. to sit; movingC. sit;move D. sitting;moving
25. Religion has a great ________ people’s behavior.
A. faith inB. division into C. effect on D. protection against
26. If the idea is wrong, the project fail, ________ good the other ideas might be.
A. though B. however C. whatever D. whichever
27. My brother telephoned the airport to make ________ of the time of the plane.
A. right B. true C. sure D. real
28. Every possible test was carried ________ to decide the nature of her illness.
A. onB. of C. out D. through

同学,很高兴回答你的问题
正确答案为：
18- 22 AABAB
23-28 ABCBCC
18.population 这个词是个集合名词,指人口整体时是不可数名词,指人口中的个体即人时是可数名词.
19.这是一个that强调句,判断是否是强调句的方法是把it is .that 去掉,如果句子还成立就是强调句.
20.这是一个定语从句,不是that强调句,方法同上,可以看出如果用that,去掉it is...that 句子不成立,所以不是强调句,是定语从句,用when引导,修饰时间.
21.likely 是极有可能的意思,其它的单词可能性不强.
22.过去分词作状语,表示被动,相当于Whe he was asked...时间状语从句.
23.虚拟语气,表示与将来事实相反的假设,如果你看到凯特,你将会告诉他什么?事实上看不到凯特.
24.ask sb.to do sth 要求某人做某事,记住ask sb.后面接to do,而let ,make,接动词原形；keep doing sth 持续做某事.
25.have a great effect on sb./sth.对.产生巨大影射.
26.however 无论如何的意思,只有它后面修饰形容词,whatever,whichever都修饰名词
27.make sure of sth 确保.,固定用法.
28.carry on 是继续,而carry out 是执行,所以根据句意,应该用carry out
有不明白的请继续追问,