31.(2008浙江) Don’t promise anything __________ you are one hundred percent sure.
A. whether B. after C. how D. unless

答案:D
解析:句意“除非你有百分百的把握,否则不要作出任何承诺”,unless表示“除非,如果不”,相当于if not,如果把后半句改为if you are not one hundred percent sure,就比较容易理解了。

32.(2008江西) Animals suffered at the hands of man __________ they were destroyed by people to make way for agricultural and to provide food for more people.
A. in which B. for which C. so that D. in that

答案:D
解析:句意“动物遭受来自人类的灭顶之灾,因为人们摧毁它们是为了开垦更多的耕地来满足更多的人对食物的需求”。at the hands of“出自……之手”,in that“因为”。

33.(2008四川) In some places women are expected to earn money __________ men stay at home and raise their children.
A. but B. while C. because D. though

答案:B
解析:句意“在一些地方人们期望女人去挣钱,而让男人在家抚养孩子”,此处while的意思是“而”,表示对比。but不强调对比,因此不恰当。

34.(2008全国II) A small car is big enough for a family of three __________ you need more space for baggage.
A. once B. because C. if D. unless

答案:D
解析:前面主句意思是:小汽车足以供一个三口之家使用。后面的从句表示你需要更多的空间装行李。主从句的关系是一种条件关系,意思是:如果你不需要更多的空间装行李的话,小汽车足以供一个三口之家使用。故选D。

35.(2007北京) Leave your key with a neighbor __________ you lock yourself out one day.
A. ever since B. even if C. soon after D. in case

答案:D
解析:in case意为“以防万一”。根据所提供的情景“Leave your key with a neighbor”可判断出表示“把你的钥匙留给你的邻居一把,以防万一有一天你被锁在外边”,故选D。

36.(2007安徽) The field research will take Joan and Paul about five months, it will be a long time __________ we meet them again.
A. after B. before C. since D. when

答案:B
解析:before意为“在……之前”。根据所提供的情景“The field research will take Joan and Paul about five months”可判断出表示“要很长时间我们才能再见面”。

37.(2007福建) You will be successful in the interview __________ you have confidence.
A. before B. once C. until D. though

答案:B
解析:once用作连词时意为“一旦……就……”。句意为“一旦你有信心,你在面试中就会成功”。

38.(2007湖南) Most birds find it safe to sleep in the trees, but __________ they have eggs or young chicks, they don’t use a nest.
A. why B. how C. unless D. where

答案:C
解析:unless引导让步状语从句,意为“如果不”。根据they have eggs or young chicks和they don’t use a nest可判断出前句是后句的条件,表示“如果它们不下蛋或没有小鸡,它们就不用窝”。

39.(2007江西) He was told that it would be at least three more months __________ he could recover and return to work.
A. when B. before C. since D. that

答案:B
解析:before引导时间状语从句,意为“在……之前”,表示“他康复后重返共组哦方位至少还要三个月的时间”。

40.(2007天津) It is difficult for us to learn a lesson in life __________ we’ve actually had that lesson.
A. until B. after C. since D. when

答案:A
解析:until引导时间状语从句,意为“直到……”,表示主句的动作一直延续到until从句中的动作发生前。