成人英语三级
单选题_____ most of the earth's surface is covered by water, fresh water is very rare and precious.A AsB OnceC IfD Although
题目
As
Once
If
Although
相似问题和答案
第1题：
B
The world is not only hungry，it is also thirsty for water． this may seem strange to you，since nearly 75% of the earth is covered with water． But about 97% of this water is sea water．Man can only drink and use the other 3% fresh water that comes from rivers，lakes，under-ground and other places． And we cannot even use all of that，because some of this fresh water has been made dirty．
At the moment，this small amount(数量) of fresh water is still enough for us． However，our need for water is getting greater and greater． Only if we take steps to solve this problem now，we can get away from a serious world water shortage later on． The people of the world cannot have an enjoyable life without enough clean water．
On one hand we should stop wasting this little water of ours，on the other hand we should find ways to reuse it，but this has not been done widely．
Today，in most large cities，water is used only once and it then returns to the sea or runs into underground places．lf we can make it clean again，it can be used once more just as if it were fresh from a spring．
But even if large cities reuse its water，we still would not have enough in the future． Where．could we turn to next for water? To the ocean! How can we do to make use of this great a-mount of sea water? We can take the salt from the water to make it fresh．
So if we take all these steps，we'll be in no danger of drying up!
( )26． Why does the writer say that the world is thirsty for water?
A． The amount of fresh water is really very small．
B． The people of the world waste too much water．
C． The people of the world have to drink a lot of water every day．
D． There are too many people in the world needing water．
26．A【解析】由第一段的描述可知，人类只有3%的、 淡水可以利用。
第2题：
A.which
B.that
C.where
D.when
第3题：
It can be learned from the passage that about four billion years ago ______.
A. the earth was in molten state
B. the earth surface temperature was above 100℃
C. the earth surface temperature was below 100℃
D. rain water could remain on the earth
43．答案为B。根据第一段最后一句及第二段内容可知，雨水在地表温度降到水的沸点以下才能停在地表，由此可知大约在四十亿年前，地表温度应在沸点以上。
第4题：
第三篇
“Life Form Found" on Saturn ' s Titan
Scientists say they have discovered hints of alien life on the Saturn'5 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 minus 17 Kelvin(minus 290 degrees Farenheit),a methane-based 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'5 surface and much too cold to support life as we know it.
Scientists had expected the Sun'5 interactions with chemicals in the atmosphere to produce a coating of
acetylene on Titan'5 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 explana-
tion,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-bio-
logical explanations.It is more likely that a chemical process,without biology,can explain these results."
A:It is as large as the Earth.
B:There is acetylene on its surface.
C:Water on it acts as a life supporting medium.
D:Hydrogen consumption is reported to be on it.
由文章第二、三段的内容可知，科学家们发现有线索显示“土卫六”上原始的外星生物 在由氢气环绕的稠密大气层中“呼吸”，也就是说这个卫星上有氢气的消耗现象。故选D。
由文章前五段的内容可知，科学家在文章开头提出“土卫六”上可能有甲烷基的生命形 态，即methane-based life，接下来的内容给出了科学家们对此说法的一系列证据来进行论证，故 选C。
由文章的最后两段中Mark Allen的话，尤其是文章最后一句“It is more likely that a chemical process ,without biology , can explain these results.”可知，科学家们认为应该用化学过程 来解释为什么“土卫六”表面没有乙炔，故选B。
由文章内容可知，科学家们提出了土星的这个最大的行星上可能有一种不依赖于水的 生命形态，并从各方面进行了证明，故选A。第5部分：补全短文
第5题：
A.The earth's surface
B.The surface of earth
C.The surface earth
D.The earth surface
第6题：
A. Seen…covered
B.Seeing…covering
C.Seen…covering
D.To see…to cover
第7题：
A.is
B.are
C.was
D.were
第8题：
According to the passage, which is true about the ocean?
A. The waters of the ocean came from rain water.
B. The ocean was formed from the, lighter rock materials.
C. The vast single ocean formed about 200 million years ago.
D. The ocean covered the whole surface of the earth at very beginning.
45．答案为A。选项A符合第二段内容。选项B与原文不符；选项C与第三段最后一句及最后一段不符；选项D与原文第二段最后一句不符。
第9题：
第三篇
“Life Form Found" on Saturn ' s Titan
Scientists say they have discovered hints of alien life on the Saturn'5 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 minus 17 Kelvin(minus 290 degrees Farenheit),a methane-based 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'5 surface and much too cold to support life as we know it.
Scientists had expected the Sun'5 interactions with chemicals in the atmosphere to produce a coating of
acetylene on Titan'5 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 explana-
tion,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-bio-
logical explanations.It is more likely that a chemical process,without biology,can explain these results."
A: Water-based life on it.
B: Methane-based life on its biggest moon.
C:A new moon moving around it.
D:Earthlike life on its biggest moon.
由文章第二、三段的内容可知，科学家们发现有线索显示“土卫六”上原始的外星生物 在由氢气环绕的稠密大气层中“呼吸”，也就是说这个卫星上有氢气的消耗现象。故选D。
由文章前五段的内容可知，科学家在文章开头提出“土卫六”上可能有甲烷基的生命形 态，即methane-based life，接下来的内容给出了科学家们对此说法的一系列证据来进行论证，故 选C。
由文章的最后两段中Mark Allen的话，尤其是文章最后一句“It is more likely that a chemical process ,without biology , can explain these results.”可知，科学家们认为应该用化学过程 来解释为什么“土卫六”表面没有乙炔，故选B。
由文章内容可知，科学家们提出了土星的这个最大的行星上可能有一种不依赖于水的 生命形态，并从各方面进行了证明，故选A。第5部分：补全短文
第10题：
1 Since heat naturally moves from hotter regions to cooler ones, the heat from the earth's center flows outwards towards the surface. In this way, it transfers to the next layer of rock. If the temperature is high enough, some of this rock melts and forms magma(岩浆). The magma ascends in its turn towards the earth's surface. It often remains well below the earth's surface, creating vast areas of hot rock. In such regions, there are deep cracks, which allow rainwater to descend underground. Some of the heated rainwater travels back up to the earth's surface where it will appear as a hot spring. However, if this ascending hot water reaches a layer of impermeable(不可渗透的)rock, it remains trapped, forming a geothermal reservoir. If geothermal reservoirs are close enough to the surface, they can be reached by drilling wells. Hot water and steam shoot up the wells naturally, and can be used to produce electricity in geothermal power plants.
2.A few geothermal power plants depend on dry-stem reservoirs which produce steam but little or no water. In these cases, the steam is piped up directly to provide the power to spin a turbine generator. The first geothermal power plant, constructed at Lardarello in Italy, was of this type, and is still producing electricity today.
3.Most currently operating geothermal power plants are either "flash" steam plants or binary(双重的)plants. Flash plants produce mainly hot water ranging in temperature from 300° to 700°Fahrenheit. This water is passed through one or two separators where released from the pressure of the underground reservoir, it "flashes" or boils into steam Again, the force of this steam provides the energy to spin the turbine and produce electricity. The geothermal water and steam are then reinjected directly back down into the earth to maintain the volume and pressure of the reservoir. Gradually they will be reheated and can then be used again.
4.A reservoir with temperatures below 300° Fahrenheit is not hot enough to flash steam but it can still be used to generate electricity in binary fluid. The steam from this is used to power the turbines. As in the flash steam plant, the geothermal water is recycled back into the reservoir.
文章(23~30)
Paragraph1_____
B.Binary plants
C.Origin of geothermal energy
D.Generation of electricity
E.Flash steam plants
F.Recyclable water and steam