第4部分：阅读理解(第31—45题，每题3分，共45分)

　　下面有3篇短文，每篇短文后有5道题。请根据短文内容，为每题确定1个最佳选项。

　　第一篇Sunspots

　　It's not surprising that sunspots(太阳黑子)were observed by ancient astronomers (天文学家).The largest soupspoon the sun can be seen without a telescope.It was not until the invention of the telescope(望远镜)in the early 17th.century，however，that systematic studies of sunspots could be undertaken.The great astronomer Galileo was among the first to make telescopic observations of sunspots

　　Sunspots are regions of extremely strong magnetic fields(磁场)found on the sun’S surface.A sunspot has a dark central core known as the umbra.The umbra is surrounded by a dark ring called the penumbra，where the magnetic field spreads outward.Sunspots appear dark because they are giving off less radiation.They are cooler than the rest of the sun’ S surface Sunspots are frequently observed’in-'pairs of in paired groups.The members of a.spot pair are identified as the leading spot and the following spot.They are identified by their position in the pair in terms of the direction in Which the sun rotates(旋转) The number of sunspots at any one time varies.A large spot group may consist of as many as 10 groups and 300 spots across the sun.The number of spots changes in a fairly regular pattern called the sunspot cycle.The largest number occurs about every 11 years.At sunspot minim L{m，there are at most just a few small spots The average lifetime of an individual spot group is roughly one solar rotation，which is about 25 days.The most persistent large slops，however can survive for two to three months.

　　31. Careful observations and systematic studies of sunspots

　　A. were made by ancient astronomers.

　　B. started in the early 17thcentury.

　　C. were made by Galileo only.

　　D. could be made without a telescope.

　　32. Sunspots are cooler than the rest of the sun's surface because

　　A. they produce less energy.

　　B. they are buried in the sun.

　　C. they are far away from magnetic fields.

　　D. they are close to magnetic fields.

　　33 The leading spot and the following spot are the names of

　　A. two large sunspots.

　　B. a large spot and a small spot.

　　C. the two spots in a spot pair.

　　D. the central core and the ring around it.

　　34. Infiniteness sunspot activity had occurred in 1857, the next one would have been in

　　A. 1858.

　　B. 1862.

　　C. 1865

　　D. 1868

　　35 In the last paragraph the word "persistent means

　　A. important.

　　B. effective.

　　C. enduring.

　　D. visible.

　　第二篇 Where Have All the Bees Gone?

　　Scientists who study insects have a real mystery on their hands.All across the country, honeybees are leaving their hives(蜂巢)and never returning.Researchers call this phenomenon colony-collapse(群体瘫痪)disorder.It is reposed that 25 to 40 percent of the honeybees in the US have vanished from their hives since last fall.So far, no one can explain why.

　　Colony collapse is a serious concern because bees play an important role in the production of about one—third of the foods we eat.As they feed，honeybees spread pollen (花粉)from flower to flower.Without this process，a plant can’t produce seeds or fruits.

　　Now，a group of scientists and beekeepers have teamed up to try to figure out what’S causing the alarming collapse of SO many colonies.They hope to find out what’S contributing to the decline and to prevent bee disappearance in the future.

　　It could be that disease is causing the disappearance of the bees.To explore that possibility, Jay Evans，a researcher at the United States Department of Agriculture (SDA)Bee Research Laboratory, examines bees taken from colonies that are collapsing.“We know what a healthy bee should Look Like on the inside.and we can look for physical signs of disease.”he says.And bees from collapsing colonies don’t look very healthy.“Their stomachs are worn down.compared to the stomachs of healthy bees，’’ ‘Evans says.It may be that a parasite(寄生虫)making the bees’digestive organs. Their immune(免疫的)systems may not be working as they should.Moreover，they have high levels of bacteria inside their bodies.

　　Another cause of colony—collapse disorder may be certain chemicals that farmers apply to kill unwanted insects on crops，says Jerry Hayes，chief bee inspector for the Florida Department of Agriculture.Some studies，he says，suggest that a certain type of insecticide(杀虫剂)affects the honeybee’S newels system and memory.“It seems like honeybees are going out and getting confused about where to go and what to do”he says.

　　1f it turns out that a disease is contributing to colony collapse，bees’genes could explain why some colonies have collapsed and others have not.In any group of bees there are many different kinds of genes.The more different genes a group has，the higher the group’S genetic diversity.So far scientists haven’t determined the role of genetic diversity in colony collapse，but it's a promising theory，says Evans.

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