理工类B级：阅读理解Where Have Allthe
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.
Colony collapse is a serious concern because bees playan important role in the production of about one-third of the foods we eat.Asthey feed，honeybees spread pollen from flower to flower.Without this process，aplant can’t produce seedsor fruits.
Now，a group of scientists andbeekeepers have teamed up to try to figure out what’s causing the alarmingcollapse of so many colonies. By sharing their expertise in honeybee behavior，health，and nutrition，team members hope to find out what’s contributingto thedecline and to prevent bee disappearance in the future.
Itcould be that disease is causing the disappearance of the bees. To explore that possibility，Jay Evans，a researcher at the United States Department ofAgriculture (USDA) Bee Research Laboratory2，examines bees taken from coloniesthat are collapsing.“We know what a healthy bee should look like on theinside，and we can look for physical signs of disease，” he says. And bees fromcollapsing colonies don’t look very healthy. “Their stomachs are worndown，compared to the stomachs of healthy bees，” Evans says.It may be that aparasite is damaging the bees digestive organs. Their immune systems may not be working as they should.Moreover，they have high levels of bacteria inside theirbodies.
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 honeybee’s nervoussystem (which includes the brain) and memory.”It seems tike honeybees are goingout and getting confused about where to go and what to do，” he says.
If itturns out that a disease is contributing to colony collapse，bees genes couldexplain why some colonies have collapsed and others have not.In any group ofbees there are many different kinds of genes.The more different genes a grouphas，the higher the group’s genetic diversity.So far scientists haven’tdetermined the role of genetic diversity in colony collapse，but it’s a promisingtheory，says Evans.
词汇：
honeybee/5hQnIbi:/n.蜜蜂 parasite/5pArEsait/n.寄生虫；寄生生物
hive/haiv/n.蜂巢；蜂箱 digestive/di5dVestiv，dai-/adj.消化的
pollen/5pClEn/n.花粉 immune/i5mju:n/adj.免疫的
beekeeper/5bi:ki:pE (r)/n.养蜂人 insecticide/in5sektisaid/n.杀虫剂
expertise/7ekspE5ti:z/n. diversity/dai5vE:siti/n.多样性
注释：
1. colony-collapse：群体瘫痪。colony有“殖民地”的意思，在此意为：a groupof the same kind of animals，plants，or one-celled organisms living or growingtogether.一群生活或生长在一起的同种动物、植物或单细胞有机体。
2. the United States Department ofAgriculture(USDA) Bee Research Laboratory：美国农业部蜜蜂研究实验室。
3. the FloridaDepartment of Agriculture：佛罗里达农业局。佛罗里达是美国东南部的一个州，濒临大西洋和墨西哥湾。
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.