题目内容
7．Honeybees are disappearing for unknown reasons around the United States．Last winter，bees disappeared from 23percent of American beekeeping businesses．Causes of the phenomenon，however，have remained a mystery．Now，scientists from several universities and the United States Department of Agriculture say they have a possible explanation for the bee decline．It is a little-known virus called Israeli acute--paralysis virus （IAPV）．The virus kills bees．Researchers in Israel first described it in 2004，but until now，bee experts haven't paid much attention to it．
When trying to find out why the bees were disappearing，a research team at Columbia University studied bee colonies （ 群体），some with and the others without decline．The research turned up large numbers of two types of fungi （真菌） once suspected of causing the bee decline．The research results，however，showed that the fungi were almost as common in colonies without a decline as they were in colonies with a decline．The researchers concluded that the two fungi probably weren't the cause．
Studies of the presence of IAPV，however，showed more interesting information．In those studies，done by a team at Pennsylvania State University in University Park，the virus showed up in 83percent of samples from colonies with symptoms （症状）．Only five percent of samples from symptomless colonies had it．
Scientists still don't know whether IAPIV can single--handedly cause the bee decline．They believe that even if the virus is making colonies sick，it could have a partner in crime．It's possible，for instance，that insects or chemicals in the environment weaken bees，making them more likely to catch IAPV．
Scientists are still trying to figure out how IAPV came to the United States．The United States currently allows bee products to be imported from Canada，Australia，and New Zealand．If it turns out that this trade is spreading disease，the rules might eventually change．
46．According to the passage，IAPV is a virus thatA．
A．hasn't attracted much attention
B．well-known to doctors and scientists
C．was first found by Austrian researchers
D．is dangerous to animals and human beings
47．The underlined word decline in the second paragraph most probably meansB．
A．disease B．decrease C．secret D．growth
48．From the third and fourth paragraphs，we know researchers draw their conclusions by means ofC．
A．calculating B．examining C．comparing D．investigating
49．The underlined sentence in the fifth paragraph probably meansC．
A．the virus could also cause other damages
B．there must be something that is the real cause
C．IAPV is not the only cause for the bee decline
D．the virus may be caused by the polluted environment
50．What still remains unknown to American scientists according to the passage？D
A．How and why to kill IAPV．
B．How to change the rules of the bee products trade．
C．Whether bee products should be imported．
D．How IAPV came to America．
分析 本文讲述了一种新型的叫做IAPV的病毒引起了美国的蜂群的消失，而具体的影响途径仍就在研究之中，科学家们甚至不清楚该病毒的来源．
解答 46．A 细节理解题．根据文章第二段内容..virus called Israeli acute--paralysis virus （IAPV）．The virus kills bees．Researchers in Israel first described it in 2004，but until now，bee experts haven't paid much attention to it．蜜蜂的消失可能是IAPV病毒导致的，但该病毒到现在并未引起重视，故选A．
47．B 词义猜测题．文章第一段表明蜜蜂无故的消失，说明蜜蜂数量的减少，后文专家对该现象做出解释，联系前后，划线单词应表示减少，与B选项同意．
48．C 推理判断题．文章第三段和第四段可得知，研究人员对蜂群和真菌的种类都进行了对比，以找出蜜蜂消失的确切原因，由此判定C为正确答案．
49．C 推理判断题．根据文章内容Scientists still don't know whether IAPV can single--handedly cause the bee decline．They believe that even if the virus is making colonies sick，it could have a partner in crime 科学家不能确定IAPIV是唯一的原因，且划线部分表示有一个犯罪时的搭档，词句表明引起蜜蜂消失的原因不止一个，故C为正确选项．
50．D 细节理解题．由文章最后一段的第一句话可得知Scientists are still trying to figure out how IAPV came to the United States 答案为D．
点评 本文是健康环保类阅读理解．做这类题材阅读理解时要求考生对文章通读一遍，做题时结合原文和题目有针对性的找出相关语句进行仔细分析，结合选项选出正确答案．推理判断题也是要在抓住关键句子的基础上合理的分析才能得出正确答案，切忌胡乱猜测，一定要做到有理有据．
