练习：
1． What is the mystery that researchers find hard to explain?
A Honeybeesare flying all across the country．
B 25-40 percent of the honeybees inthe US have died．
C Honeybees are leaving their hives and do not return．
D Honeybee hives are in disorder．
2． Why are researchersseriously concerned with the phenomenon of colony-collapsedisorder?
A Because honeybees produce one-third of the foods we eat．
B Becausehoneybees feed on flowers．
C Because honeybees eat seeds of flowers．
D Both B and C．
3． What are the possible causes of colony-collapsedisorder given by the scientists?
A Worsening environment．
B Diseaseand chemicals．
C Dwindlingnumber of flowers around．
D Changes ingenes’ structures．
4． According to the fifth paragraph，which of thefollowing about bees’ genes istrue?
A Bees’ genes allow them toexpand their colonies．
B Bees’genes help keep them in their hives．
C Bees’genes make them fly from flower to flower．
D Bees’genes couldexplain the collapse of some colonies．
5． What explanation is given byJerry Hayes to the phenomenon?
A Farmers apply certain chemicals to killunwanted bees．
B The insecticide destroys the honeybee’s nervous system．
C The insecticide affects the honeybee’s memory．
D All of theabove．
答案与题解：
1． C 短文第一段的第一句和最后一句告诉我们，昆虫学家正面临一个不可解释的谜。第二句解释了这个谜，给出了答案。
2． A 短文第二段的第一句提供了答案。蜜蜂传播花粉能使植物结果，因此为人类提供食物。
3． B 第四段的开头是It could be thatdisease is causing the disappearance of the bees．第五段的开头是Another cause ofcolony-collapse disorder may be certain chemicals that，这是科学家给出的两个可能造成这种现象的原因。
4． D 第六段的句子：bees’genes could explain why some colonies have coilapsed andothcrs have not。这是选择D的依据。选项A、B、C的内容文章中都没有出现，所以不是答案。
5． D 第五段描述了另一个可能的原因，即农夫使用的杀虫剂可能破坏了蜜蜂的神经系统和记忆。所以D是正确选择。
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