2013年英语四级阅读试题及答案3

　　Heroin addictions today is found chiefly among young men of minority groups in ghetto(犹太人区)areas.Of the more than 60,000 known addicts,more than half live in New York State.Most of them live in New York City.Recent figures show that more than half of the addicts are under 30 years of age.?

　　Narcotic addiction in the United States is not limted to heroin users.Some middle-aged and older people who take narcotic drugs regularly to relieve pain can also become addicted.So do some people who can get drugs easily,such as doctors,nurses,and pharmacists.Studies show that this type of addict has personality and emotional problems very similar to those of other regular narcotic users.?

　　Many addicts admit that getting a continued supply is the main object of their lives.An addict’s concentration on getting drugs often prevents continuing an education or working at a job.His health is often poor.He may be sick one day from the effects of withdrawal and sick the next day from an overdose.Statistics show that an addict’s life span may be shortened by 15 to 20 years.The addict is usually in trouble with the family and almost always in trouble with the law.?

　　Some studies suggest that many of the known narcotic addicts had some trouble with the law before they became addicted.Once addicted,they may become even more involved with crime because it costs so much to support the heroin habit.?

　　Most authorities agree that the addict’s involvement with crime is not a direct effect of the drug itself.Turning to crime is usually the only way to get that much money.The addicts’ crimes are nearly always thefts or other crimes against?property.?

　　Federal penalties for illegal narcotics usage were established under the Harris on Act of 1914.The Act provides that illegal possession of narcotics is punishable by fines and/or imprisonment.Sentences can range from 2 to 10 years for the first offense,5 to 20 years for the second,and 10 to 20 years for further offenses.?

　　Illegal sale of narcotics can mean a fine of $20,000 and a sentence from 20 to 40 years for later offenses.A person who sells narcotics to someone under 18 is refused parole and probation,even for the first offense.If the drug is heroin,he can be sentenced to life imprisonment or to death.

　　Scientists say they have discovered hints of alien life on the Saturn's moon. The discovery of a sort of life was announced after researchers at the US space agency,NASA,analyzed data from spacecraft Cassini,which pointed to,the existence of methane-based form of life on Saturn's biggest moon.

　　Scientists have reportedly discovered clues showing primitive alien beings are"breathing" in Titan's dense atmosphere filled with hydrogen.

　　They argue that hydrogen gets absorbed before hitting Titan's planet-like surface covered with methane lakes and rivers. This,they say,points to the existence of some"bugs" consuming the hydrogen at the surface of the moon less than half the size of the Earth.

　　"We suggested hydrogen consumption because it's the obvious gas for life to consume on Titan,similar to the way we consume oxygen on Earth,"says NASA scientist Chris McKay."If these signs do turn out to be a sign of life,it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth."

　　To date,scientists have not yet detected this form of life anywhere,though there are liquid- water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin(minus 290 degrees Farenheit),a methanebased organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan's surface and much too cold to support life as we know it.

　　Scientists had expected the Sun's interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan's surface. But Cassini detected no acetylene on the surface.

　　The absence of detectable acetylene on the Titan's surface can very well have a non-biological explanation,said Mark Allen,a principal investigator of the NASA Titan team.

　　"Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed,"Allen said. "We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process,without biology,can explain these results."

　　1. Passage One

　　Unless we spend money to spot and prevent asteroids(小行星)now，one might crash into Earth and destroy life as we know it，say some scientists.?

　　Asteroids are bigger versions of the meteoroids(流星)that race across the night sky.Most orbit the sun far from Earth and don't threaten us.But there are also thousands whose orbits put them on a collision course with Earth.?

　　Buy $ 50 million worth of new telescopes right now.Then spend $ 10 million a year for the next 25 years to locate most of the space rocks.By the time we spot a fatal one，the scientists say，we'll have a way to change its course.?

　　Some scientists favor pushing asteroids off course with nuclear weapons.But the cost wouldn't be cheap.?

　　Is it worth it? Two things experts consider when judging any risk are: 1) How likely the event is; and 2) How bad the consequences if the event occurs. Experts think an asteroid big enough to destroy lots of life might strike Earth once every 500，000 years. Sounds pretty rare-but if one did fall，it would be the end of the world.“If we don't take care of these big asteroids，they'll take care of us，”says one scientist.“It's that simple.”?

　　The cure，though，might be worse than the disease. Do we really want fleets of nuclear weapons sitting around on Earth?“The world has less to fear from

　　doomsday(毁灭性的) rocks than from a great nuclear fleet set against them，” said a New York Times article.