Illegal sale of narcotics can mean a fine of $20,000 and a sentence from 20 to 40 years for later person who sells narcotics to someone under 18 is refused parole and probation,even for the first 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\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\consuming the hydrogen at the surface of the moon less than half the size of the Earth.
\suggested hydrogen consumption because it's the obvious gas for life to consume on Titan,similar to the way we consume
oxygen on Earth,\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.
\conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed,\said. \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 orbit the sun far from Earth and don't threaten there are also thousands whose orbits put them on a collision course with Earth.
Buy $ 50 million worth of new telescopes right spend $ 10 million a year for the next 25 years to locate most of the space 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 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.
21. What does the passage say about asteroids and meteoroids A) They are heavenly bodies different in composition. B) They are heavenly bodies similar in nature. C) There are more asteroids than meteoroids. D) Asteroids are more mysterious than meteoroids.
[答案及分析]：［B］文章第二段第一句明确指出“小行星和划破夜空的流星是性质一样的物质，只是体积大些。”解题的关键是对version的理解。
22. What do scientists say about the collision of an asteroid with Earth
A) It is very unlikely but the danger exists.
B) Such a collision might occur once every 25 years.
C) Collisions of smaller asteroids with Earth occur more often than expected.
D) It's still too early to say whether such a collision might occur..
[答案及分析]：［A］文章倒数第二段对小行星撞击地球的可能性作出了很形象的描述，每50万年才可能有一次，但一旦发生，将是地球末日。
23. What do people think of the suggestion of using nuclear weapons to alter the course of asteroids
A) It sounds practical but it may not solve the problem.
大学英语四级阅读理解试题及答案
