Oxygen is a kind of gas, we couldn’t live. Awithout itB without that C without which D if not 题目和参考答案——青夏教育精英家教网—

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Oxygen is a kind of gas, ______ we couldn’t live.
Awithout itB without that C without which　D if not

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IS THERE LIFE ON EARTH?

There was great excitement on the planet of Venus(金星) this week. For the first time Venusian scientists managed to land a satellite on the planet Earth, and it has been sending back signals as well as photographs ever since.?

The satellite was directed into an area known as Manhattan (named after the great Venusian astronomer Prof. Manhattan, who first discovered it with his telescope 20 000 light years ago).Because of excellent weather conditions and extremely strong signals, Venusian scientists were able to get valuable information as to feasibility(可行性) of a manned flying saucer(飞碟) landing on Earth.A press conference was held at the Venus Institute of Technology.?

“We have come to the conclusion,based on last week's satellite landing,” Pro. Zog said,“that there is no life on the Earth.”?

“How do you know this?” the science reporter of the Venus Evening Star asked. ?

“For one thing, Earth's surface in the area of Manhattan is composed of solid concrete(混凝土)and nothing can grow there. For another, the atmosphere is filled with carbon monoxide(一氧化碳) and other deadly gases and nobody could possibly breathe this air and survive.”?

“What does this mean as far as our flying saucer program is concerned?”?

“We shall have to take our own oxygen with us, which means a much heavier flying saucer than we originally planned. ”

“Are there any other hazards that you discovered in your studies?”?

“Take a look at this photo. You see this dark cloud floating over the surface of Earth? We call this the Consolidated Edison Belt. We don't know what it is made of, but it could give us a lot of trouble and we shall have to make further tests before we send a Venus Being there.”?

“If what you say is true, won't this set back the flying saucer program several years?”?

“Yes, but we shall proceed as soon as the Grubstart gives us the added funds.”?

“Prof. Zog, why are we spending billions and billions of zilches to land a flying saucer on Earth when there is no life there?”?

“Because if we Venusians can learn to breathe in an Earth atmosphere, then we can live anywhere.”

During the week of great excitement the Venusian scientists succeeded in getting important information on whether they can_______.

A. land a satellite with Venus astronauts on Earth

B. make a first?rate flying saucer?

C. get a Earth Being to Venus

D. direct a flying saucer into Manhattan?

According to Prof.Zog,the Venusians will have to take their own oxygen with them when they carry out their flying saucer program because_______.?

A. they need it on their way to the planet of Earth?

B. the Earth's atmosphere is filled with deadly gases?

C. oxygen is far from enough in the area of Manhattan where the saucer is to land?

D. there is no air on the planet of Earth?

The “dark black cloud” on the photograph refers to_______.?

A. the polluted air floating over the surface of Earth?

B. the mass of tiny drops of water floating above Earth?

C. the things that are unknown to everybody?

D. the dark clouds gathering before a storm breaks?

The author wishes to call our attention to the fact_______.?

A. that modern man has polluted his environment to such an extent that he might destroy himself if he went on like this?

B. that there is no point in spending billions and billions of zilches to land a flying saucer on Earth?

C. that pollution has become so serious a problem on Earth that even Venusians find life there unbearable?

D. that it is difficult, if not altogether impossible, to land a manned flying saucer on Earth

    As bananas ripen， the green skin turns ye11ow gradually. Chemical changes occur in the f1esh of the fruit as well：starch（淀粉）changes to sugar；pectin（果胶）breaks down，losing its stiffness； and the f1esh softens.
Is ripening fruit a self－contained system， or is the rate of these changes affected by the environment？ We designed the experiment below to see if different atmospheres， produced by different packaging， affected the rate of ripening. You will vary the atmosphere surrounding unripe bananas and observe the effect on the ripening process。
Now set up the bananas in their environments as follows：
1. Put two green bananas in a paper bag and fo1d the top over to seal out the air.
2．Put one green banana and the very ripe banana in the other paper bag and fold over the top.
3. Put two green bananas in a plastic bag and seal it.
4. Wrap（包）one green banana tightly in a plastic bag.
5. Leave one green banana exposed to the air.
Leave the fruit a1one or five days to ripen. Ripening fruit“breathes”． This means that it takes up oxygen and gives off C02. Oxygen is extremely important and necessary for the chemical reactions involved in ripening. In addition, ripening fruit gives off another gas, called ethylene（乙烯）. Not only is ethylene a product of ripening fruit, it also promotes the further ripening of the fruit.
Paper bags tend to keep the ethylene in, but they allow oxygen and ethylene to pass through slowly. Plastic bags do not allow the free flow of oxygen or ethylene. In this experiment, the green banana in paper bag with the ripe banana should ripen most quickly. The green bananas in the paper bag should ripen faster than the bananas in the plastic bag. The banana left exposed to air has an unlimited supply of oxygen, so it will turn brown most quickly. You will notice that the side of this banana that rests on the counter will ripen more quickly than the other sides, because it has the
closest contact（接触）with its own ethylene. The banana that is tightly wrapped in plastic has no oxygen supply and should ripen most slowly. Now can you see why bananas are sealed in plastic in many supermarkets？
72. What makes the green banana in Bag 2 ripen more quickly than the ones in Bag 1？
A. Ethylene from the very ripe banana.            B. The free flow of oxygen or ethylene
C. C02 from the very ripe banana.                     D. The limitation of oxygen supply.
73. How can we slow down the ripening of bananas exposed to the air？
A. To rest them on the counter.                                   B. To keep them in the basket.
C. To put them on the ground.                                     D. To hang them up from the ceiling
74. It can be concluded from the passage that          .
A. the ripening banana is a self-contained system
B. the rate of ripening bananas is affected by the environment
C. wrapped bananas experience no chemical changes to ripen
D. ripening bananas give off oxygen, C0, and ethylene
75. Why are bananas sealed in plastic in many supermarkets？
A. To make them ripen more quickly.                B. To make them ripen more slowly.
C. To make banana flesh soften.                        D. To turn green bananas yellow.

For years , many people would not believe that smoke could attack so many parts of the body in so many ways . Study shows , however , that tobacco isn’t one single thing . At least 60% of it is gas—20 different kinds of gas . And one of these is the deadly carbon monoxide (CO) （一氧化碳）.
In factories , the amount of this gas in the air is measured , and it must be kept under fixed , safe level . But there is 640 times this safe amount in cigarette smoke .
Oxygen is carried through your body by the red blood cells . But this poison gas , CO, will get to the blood cells before the oxygen can . So , if you smoke your blood carries five to ten times more of this deadly gas than is normal . To make up for this , your body must make more red cells .
The oxygen in your blood passes into your tissues（组织）. But here again CO makes trouble . It keeps the oxygen from passing into your tissues as fast as it should . Because of this , cigarette country is always about 8000 feet above sea level . Someone who smokes and lives at sea level gets as little oxygen as a nonsmoker at an altitude（高度）of nearly two miles .This happens to everyone who smokes , no matter how old or how young . Anyone who competes in sports can tell you that those who smoke run out of breath more quickly than those who do not .
1．The gas amount in cigarette smoke is______________.
A．640 times higher than the gas safe levels in factories
B．640 times lower than the gas safe levels in factories
C．640 times as much as that in factories
D．as dangerous as that in factories
2．If you smoke , ______________ .
A．your blood carries more oxygen than is normal
B．your blood carries much more CO than is normal
C．you can have five to ten times of blood than usual
D．your blood will be poisonous
3．Those who smoke______________.
A．all live at sea level
B．don’t live at an altitude of two miles
C．breathe as much oxygen as non-smokers
D．only get the same amount of oxygen at the sea level as non-smokers at an altitude of nearly 2 miles
4．Smokers are______________.
A．easily hurt B．easily excited C．easily tired D．healthy

The earth is the only planet that scientists are certain has life .What does the earth have that the other planets don’t ? For one thing , the earth has just the right temperature . As the third planet from the sun , the earth seems to be just the right distance away . The planets that are closer to the sun are so hot that their surfaces bake in the sun . The farthest planets are cold balls .

When the earth developed— which scientists believe may have happened about billions of years ago , many gases covered the earth . The gases caused the earth to be hot . But something wonderful happened . The temperature was just right for thick clouds to form . It rained very hard for a very long time . This gave the earth its oceans . Water made it possible for plants to grow . The plants created oxygen in the atmosphere . Oxygen is the gas that humans and animals breathe .

Only one other planet in the solar system seems to be something like the earth . That planet is Mars . Mars is smaller than the earth , and it is quite a bit cooler . But it is not too cold for humans . On some days , the temperatures are as cold as a winter day in the northern United States . If you wore a special spacesuit , you could walk around on Mars . You would have to bring your own air to breathe , though . The air on Mars is too thin to breathe . Mars has the largest volcano in the solar system . It is sixteen miles high . The highest volcano on the earth is five miles high . The most unexpected sight on Mars is dried-up river beds . Scientists believe that Mars was once much wetter that it is now . Does this mean there could have been living things on Mars ? Scientists are not sure , but there has been no sign so far .

1.It is the on the earth that makes life possible .

A．temperature B．water C．oxygen D．temperature , water and oxygen

2.The underlined phrase “ the third planet ” means .

A．the sun B．the earth C．the moon D．Mars

3.Which planet in the solar system is most like the earth ?

A．Mars . B．Moon . C．Sun . D．Mars and Moon .

4.Which of the following is TRUE ?

A．The earth has a history of about 4 million years .

B．There is no air on Mars .

C．The largest volcano on Mars is over three times higher than the highest one on the earth

D．Scientists believe there are living things on Mars .

5.The best title for the passage should be .

A．Living Things on Our Earth B．The Moon

C．Living Things on the Moon D．Mars Is Most Like the Earth

For years scientists have been concerned about the effects of air pollution on the earth's natural conditions. Some believe the air inside many houses may be more dangerous than the air outside. It may be one hundred times worse.

Indoor air pollution can cause a person to feel tired,to suffer eye pain, headache and other problems.Some pollutants(污染物)can cause breathing disorders,diseases of blood and even cancer. Most scientists agree that every modern house has some kind of indoor pollution.People began to notice the problem in the early 1970s.It is said that when builders began making houses and offices they did not want to waste energy.To do this,they built buildings that limited the flow of air between inside and outside.They also began using man-made building materials.These materials are now known to let out harmful gases.As the problem became more serious, scientists began searching for a way to deal with it.They discovered a natural pollution control system for building－green plants.Scientists do not really know how plants control air pollution.They believe that a plant's leaves absorb or take in the pollutants.In exchange the plant lets out oxygen through its leaves and through its tiny organizations on its roots.Scientists suggest that all buildings should have one large plant or several small plants inside for every nine square metres of space.Studies of different plants show that each absorbs different chemicals.So the most effective way to clean the air is to use different kinds of plants.Having green plants inside your house can make it a prettier and healthier place.

77.What is the topic of the passage?

A.Air pollution.

B.Green plants indoors.

C.Indoor air pollution.

D.Environment protecting.

78.What makes indoor air pollution more harmful than that of the air outside?

A.The limited flow of air indoors.

B.Man-made building materials.

C.Fewer green plants inside houses.

D.The energy-saving materials indoors.

79.The most effective way to clean the air is to use different kinds of plants because______.

A.they can make houses pettier and healthier

B.they may let out oxygen which people need

C.they can take in all kinds of indoor pollutants

D.they can absorb different harmful indoor chemicals

80.Which of the following is implied but NOT stated?

A.keep windows open and let fresh air in.

B.Scientists have a clear idea how plants control air pollution.

C.Oxygen is let out through the leaves and roots of the plants.

D.Green plants are a natural pollution control system for building.

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