Searching Venus' sky From the moon to Mars，scientists have been hunting for alien life in the solar system for decades.
However，Venus was not regarded as an ideal place because of its hot temperature and dry atmosphere.
But a recent discovery of traces of a gas in the clouds of Venus has excited astronomers，as it may serve as a potential sign of life.
On Sept 14，the Royal Astronomical Society of Canada announced that scientists have detected phosphine（磷化氫） in the clouds of Venus.Phosphine is a colorless，toxic（有毒的）gas that has an odor of garlic.Though toxic，it is viewed as a possible sign of life because on Earth the gas is made by microorganisms that live in oxygen-free environments.
"I was very surprised - stunned，in fact，" astronomer Jane Greaves of Cardiff University in Wales and lead author of the research，told MSN. "There is a chance that we have detected some kind of living organism in the clouds of Venus."
This layer of clouds is about 48 kilometers above the Venus surface，with its temperature ranging from 30 to 200 degrees Fahrenheit （about -1 to 93℃）.Scientists have speculated that if life exists on Venus，this cloud deck（云蓋）is likely the only place where it would survive.
Scientists went through every possibility that could have led to the formation of phosphine gas in Venus' clouds，including volcanoes，lightning strikes，small meteorites（隕石）falling into the atmosphere.But they ruled all of them out.It was concluded that there is no explanation for the existence of this gas in Venus' clouds，other than the presence of life，USA Today reported.
Although the detection of phosphine is not robust（強有力的）evidence for life，this finding is great enough to change scientists' view on Venus，which is thought to be a completely inhospitable planet.
What signs of life we looking for？
（1）、Liquid water：It can dissolve a huge range of molecules needed for life and facilitate their chemical reactions.
（2）、Mild temperatures：Temperatures higher than 122 C will destroy most complex organic molecules，and make it almost impossible for carbon-based life to form.
（1）What is the text mainly about？ AA
A．A newly detected gas may indicate possible existence of life on Venus.
B．Scientists found the most hospitable place on Venus.
C．The environment on Venue changed in favor of life.
D．Phosphine formed on Venus means alien life is present.
（2）What can we learn about phosphine from the text？ CC
A．It has no smell at all.
B．It only exists on Venus.
C．It can be produced by microorganisms.
D．It is a sign of the existence of oxygen.
（3）What can we infer from paragraphs 5 and 6？ DD
A．Various living organisms have been detected on Venus.
B．The higher the cloud is above Venus，the warmer it is.
C．The cloud deck is rich in phosphine.
D．If life exists on Venus，it is likely in the cloud deck.
（4）What did scientists conclude about the phosphine gas detected on Venus？ BB
A．It could be formed as a result of the falling of meteorites.
B．It could be a sign that there is life in Venus' clouds.
C．It could be caused by volcanoes and lighting strikes.
D．It proves that Venus is another hospitable planet.
【答案】A；C；D；B
【解答】
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發(fā)布：2024/4/20 14:35:0組卷：4引用：3難度：0.5
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