Soot (煤烟) and Snow：a Hot Combination（难度B/C级，偏向B级）

　　New research from NASA scientists suggests emissions of black soot alter the way sunlight reflects off snow．According to a computer simulation，black soot may be responsible for 25 percent of observed global warming over the past century．
　　Soot in the higher latitudes of the Earth，where ice is more common，absorbs more of the sun’s energy and warmth than an icy,white background．Dark-colored black carbon，or soot，absorbs sunlight, while lighter colored ice reflects sunlight．
　　Soot in areas with snow and ice may play an important role in climate change．Also，if snow and ice covered areas begin melting，the warming effect increases，as the soot becomes more concentrated on the snow surface．”This provides a positive feedback．as glaciers and ice sheets melt，they tend to get even dirtier,”said Dr．James Hansen，a researcher at NASA's Goddard Institute for Space Studies．New York．
　　Hansen found soot’s effect on snow albedo (solar energy reflected back to space)，which may be contributing to trends toward early springs in the Northern Hemisphere，such as thinning Arctic sea ice，melting glaciers and permafrost．Soot also is believed to play a role in changes in the atmosphere above the oceans and land．
　　“Black carbon reduces the amount of energy reflected by snow back into space，thus heating the snow surface more than if there were no black carbon‘，”Hansen said．Soot’s increased absorption of solar energy is especially effective in warming the world’s climate．
　　“This forcing is unusually effective，causing twice as much global warming as a carbon．dioxide forcing of the same magnitude．”Hansen noted．
　　Hansen cautioned，although the role of soot in altering global climate is substantial，it does not alter the fact that greenhouse gases are the primary cause of climate warming during the past century．Such gases are expected to be the largest climate forcing for the rest of this century．
　　The researchers found that observed warming in the Northern Hemisphere was large in the winter and spring at middle and high latitudes．These observations were consistent with the researchers’climate model simulations．which showed some of the 1argest warming effects occurred when there were heavy snow cover and sufficient sunlight．
 

 
6．Hansen cautioned that greenhouse gases__.
7．  Black soot covered snow and ice__.
8．  A soot forcing is unusually effective，which__.
A produces much more global warming than a carbon-dioxide forcing of the same magnitude
B  contributed to 25 percent of observed global warming
C  Can produce greenhouse gases
D  absorb more of sun’s energy and warmth than white background
E  still surpass soot in warming the world’S climate during the last century来源：考试大
F  Can be seen mostly in the Northern Hemisphere
 
　　第四部分：阅读理解（每题3分，共45分）来源：考试大

　　下面有3篇短文，每篇短文后有5道题，每道题后面有4个选项。请仔细阅读短文并根据短文回答其后面的问题，从4个选项中选择1个最佳答案涂在答题卡相应的位置上。

Inspecting a Used Car（难度B/C级）

　　The scariest part of buying a used car is not being completely sure of what condition it’s in．A car that’s been in a major accident is always a bigger risk，but sellers often try to hide this information．Andrew Bleakley, evaluator-inspector，runs a mobile vehicle inspection service in Montreal．For about$80 he will perform a full，unbiased inspection on a used vehicle．In his 10 years as a professional inspector, Bleakley has seen a lot．He warns．“Watch out for dealer demonstration vehicles which are used．not new．They may have been in a collision．”He adds that it is not uncommon in Ontario and Quebec especially for unscrupulous sellers to roll back the odometer or to even disengage it．Bleakiey has special tools to check for this．
　　Bleakley always recommends hiring all independent technician to inspect the condition of a used car before you buy it．The problem is finding someone qualified to do the inspection．Which he says generally doesn’t mean just any mechanic．A thorough mechanical inspection includes checking the compression，all major systems，including the engine，electrical and charging systems，transmission and drive line，fluids，brakes，suspension，and steering．Essential，too, is all inspection of the car’s body and finally a road test．There are，however, a few things everyone can do before buying a used Car：
　　Do a visual check of the car．Look at the right rear door hinges．If they are very worn, or the door doesn’t close well，the car may have been used as a taxi．Holes in the roof could mean the car was used for deliveries．
　　Check for oil leaks on the pavement．Note that leaks are not necessarily a significant
problem--it depends on the cause．
　　Don’t assume that new．100king brake and accelerator pedals mean the car hash’t been
driven much．Resellers know people check these details and can buy new pads for around$6．
　　Copy down the vehicle identification number(VIN)。a 17-character combination of
numbers and letters，from the vehicle’s dashboard．In Ontado，ask the dealer or seller for the Used Vehicle Information Package．This gives details of previous owners，any outstanding liens on the car, and the fair market value of the vehicle.

词汇：来源：考试大
collision n．碰撞；碰撞事故
odometer n．里程表
compression n．压缩；压缩量来源：考试大
brake n．刹车
pedal n．踏脚
lien n．扣押权
unscrupulous adj．不择手段的
disengage v．松开；使脱离
transmission n．传输
suspension n．悬架
hinge n．铰链
dashboard 仪表板来源：考试大
 
1. According to the passage, in buying a second-hand vehicle it is most important to know__.
A)How long it has been used.
B)What color it is.
C)Whether it has been in a collision.
D)Whether it leaks oil.来源：考试大
 
2. All of the following are mentioned as tricks which dishonest second-hand car dealers may play upon their customers EXCEPT___.
A)To re-paint the car.
B)To roll back the odometer.
C)To replace the old pedal.
D)To disengage the odometer.
 
3. “An independent technician” in the first sentence of the second paragraph means__.
A)A technician who checks a car free of charge.
B)A technician who learned his trade all by himself.
C)A technician who works for a particular car-dealer.
D)A technician who runs his own inspection service.
 
4.According to Bleakly, before buying a used car all the inspection work can ___.
A)Be done by mechanic together with the dealer.
B)Only be done by a qualified mechanic
C)Be done by the buyer himself.来源：考试大
C)Be done by a qualified mechanic together with the buyer.
 
5. According to the passage, from which of the following can the buyer obtain reliable information of the previous owner?
A)The vehicle identification number.
B)The unbiased inspector.
C)The second-hand car dealer.
D)The Used Vehicle Information Package.