阅读下面的短文。每篇短文的后面有五个问题，每个问题有四个备选答案。请根据短文的内容选择最佳答案。每个试题计3分,共计15分。
Scientists who study insects have a real mystery on theirhands.All across the country，honeybees are leaving their hives and neverreturning. Researchers call this phenomenon colony-collapse1 disorder.Accordingto surveys of beekeepers across the country，25 to 40 percent of the honeybeesin the United States have vanished from their hives since last fall.So far，noone can explain why.
Now，a group of scientists andbeekeepers have teamed up to try to figure out whats causing the alarmingcollapse of so many colonies. By sharing their expertise in honeybee behavior，health，and nutrition，team members hope to find out whats contributingto thedecline and to prevent bee disappearance in the future.
Another cause of colony-collapse disorder may be certain chemicalsthat farmers apply to kill unwanted insects on crops，says Jerry Hayes，chief beeinspector for the Florida Department of Agriculture3.Some studies，hesays，suggest that a certain type of insecticide affects the honeybees nervoussystem and memory.It seems tike honeybees are goingout and getting confused about where to go and what to do, he says.
词汇：5hQnIbi:5pArEsaitp
hiven.蜂巢;蜂箱 digestiveadj.消化的5pClEni5mju:np
beekeepern.养蜂人 insecticiden.杀虫剂7ekspE5ti:zdai5vE:sitip
专门知识，专长注释：
2. the United States Department ofAgriculture Bee Research Laboratory：美国农业部蜜蜂研究实验室。
练习：
A Honeybeesare flying all across the country.
C Honeybees are leaving their hives and do not return.
2. Why are researchersseriously concerned with the phenomenon of colony-collapsedisorder?
B Becausehoneybees feed on flowers.
D Both B and C.
A Worsening environment.
C Dwindlingnumber of flowers around.
4. According to the fifth paragraph，which of thefollowing about bees genes istrue?
B Beesgenes help keep them in their hives.
D Beesgenes couldexplain the collapse of some colonies.
A Farmers apply certain chemicals to killunwanted bees.
C The insecticide affects the honeybees memory.
答案与题解：
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。
4. D 第六段的句子：beesgenes 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。