25.We cannot figure out _____________ quite a number of insects,birds,and animals are dying out.
A.that B.as C.why D.when
解析：why引导宾语从句，并在从句中作原因状语。
答案：C
24.What surprised me was not what he said but _____________he said it.
A.the way B.in the way that C.in the way D.the way which
解析：the way是先行词，后接定语从句时，关系词可以是that或in which或省略。
答案：A
23.You should try to get a good night’s sleep _____________much work you have to do.
A.however B.no matter C.although D.whatever
解析：however引导让步状语从句，也可以用no matter how。
22.She will have to_____________herself to the new condition.
ge B.fit C.adjust D.suit
解析：adjust oneleft to sth.“使自己适应……”。
21.If you buy more than ten,they knock 20 pence off_____________.
A.a price B.price C.the price D.prices
解析：特指在原来的价格的基础上降价20便士。
20.You _____________be tired-you’ve only been working for an hour.
A.must not B.won’t ’t D.may not
解析：用在否定句中表示推测和判断，用can。must用在肯定句中表示判断和推测。
19.The evening news comes on at Seven o’clock and_____________only thirty minutes.
A.keeps tinues C.finishes D.lasts
解析：表示时间的持续。
答案：D
18.I lay in the sofa,enjoying the beautiful music Jack had_____________out of his DVD.
e B. come C.it coming ing
解析：本题考查的是“have+宾语+v.-ing”作宾语补足语的用法。定语从句中省去了宾语which。C项多了一个代词it。
17.-I was riding along the street and all of a sudden,a car cut in and knocked me down.
-You can never be _____________careful in the street.
A.much B.very C.so D.too
解析：该题考查副词作程度状语的情况。can not/can never …too…的意思是“怎么……也不过分”。
16.Arabic is written in the opposite direction to English,_____________,from right to left.
A.that is B.which is C.what is D.as it is
解析：本题考查that is作插入语的用法，其意思是“就是说，即”。
