题目内容

The oxygen equipment made it possible for the climbers to rest and sleep at very high ________．

A.
level
B.
heights
C.
altitudes
D.
atmosphere

C
题干意思为：供氧设施使得登山队员有可能在高处休息和睡觉。level“水平”，atmosphere“环境”，显然A, D两项不正确。而height指“高度”，altitude可指“高处”，而题干所指的是“休息和睡觉的场所(地方)”，并非“休息和睡觉的高度”，且altitude为可数名词。

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Scientists in Israel have discovered a new way to test for water pollution by "listening" to what the plants growing in water have to say．By shining a laser beam(激光束) on the tiny pieces of algae(海藻) floating in the water, the researchers said they hear sound waves that tell them the type and amount of pollution in the water．

"It is a red light, telling us that something is beginning to go wrong with the quality of water," said Zvy Dubinsky, an aquatic biologist at Israel's Bar Ilan University．"Algae is the first thing to be affected by a change in water quality．"

As water sources deteriorate worldwide, the testing of algae could be used to monitor water quality faster, more cheaply and more accurately than techniques now in use, Dubinsky said．The secret is to measure the rate of photosynthesis(光合作用) in the algae, meaning the plant's ability to transform light into energy．During photosynthesis, plants also release oxygen into the air．

Dubinsky's technique is easy to perform because of the over-abundance of algae in the planet's water．Most of the oxygen in the atmosphere comes from algae．A prototype tester shoots a laser beam at water samples to stimulate photosynthesis in the algae．But not all of the laser's heat is used．

Depending on the condition of the algae and the rate of photosynthesis, some of the heat is shot back into the water, creating sound waves, Dubinsky said．With a special underwater microphone, researchers are able to analyze the strength of the sound waves and determine the health of the algae and the condition of the surrounding water．

"Algae suffering from lead poisoning, like waste discharged from battery and paint manufacturing plants, will produce a different sound than those suffering from lack of iron or exposure to other toxins," said researcher Yulia Pinchasov．

72．To study water quality, scientists choose algae mainly because ．

A．algae is most easily affected by pollution

B．most oxygen is produced by algae

C．the amount of algae is decreasing

D．algae is a kind of plant floating in the water

73．When Dubinsky studied water quality, he mainly focused on ．

A．the amount of laser used by algae

B．the rate of photosynthesis in the algae

C．the condition of the algae

D．the heat of laser used by algae

74．After the study, scientists proved that ．

A．the increase in population is caused by lack of water

B．global warming causes water resources to reduce worldwide

C．algae can show the type and amount of pollution in the water

D．algae is dying out in the ocean around the world

75．What would be the most suitable title for the passage?

A．Water pollution is reduced with the growth of algae

B．Pollution makes it hard for plants to make photosynthesis

C．Water pollution affects the growth of marine plants

D．Scientists listen to plants to find pollution

Scientists in Israel have discovered a new way to test for water pollution by “listening” to what the plants growing in water have to say.

By shining a laser beam (激光束) on the tiny pieces of algae floating in the water，the researchers said they hear sound waves that tell them the type and amount of contamination (致污物) in the water.

“It is a red light，telling us that something is beginning to go wrong with the quality of water，” said Zvy Dubinsky，an aquatic biologist at Israel’s Bar Ilan University.“Algae is the first thing to be affected by a change in water quality.”“The secret，” he said，“is to measure the rate of photosynthesis (光合作用) in the algae，meaning the plant’s ability to transform light into energy.” During photosynthesis，plants also release oxygen into the air.

Dubinsky’s technique is easy to perform because of the over?abundance of algae in the planet’s water.Most of the oxygen in the atmosphere comes from algae.A prototype tester that occupies about one square meter of a laboratory desktop，shoots a laser beam at water samples to stimulate photosynthesis in the algae.But not all of the laser’s heat is used.Depending on the condition of the algae and the rate of photosynthesis，some of the heat is shot back into the water，creating sound waves，Dubinsky said.With a special underwater microphone，researchers are able to analyze the strength of the sound waves and determine the health of the algae and the condition of the surrounding water.

“Algae suffering from lead poisoning，like waste discharged from battery and paint manufacturing plants，will produce a different sound than those suffering from lack of iron or exposure to other toxins，” said researcher Yulia Pinchasov.She said that testing algae photosynthesis can determine water quality more accurately and easily than labor?intensive methods now used like chemical and radioactive carbon testing.

1.The underlined word “algae” in Paragraph 2 probably refers to a kind of________.

A．instrument? B．plant

C．wood? D．pollutant

2.Why is the algae tested?

A．Because it floats on the water.

B．Because it can have photosynthesis.

C．Because it is the first to be polluted.

D．Because it can produce different sounds.

3.We can infer from the passage that________.

A．algae can produce a loud sound when polluted

B．algae can die easily from pollution

C．photosynthesis of the algae can only be caused by sunlight

D．photosynthesis of the algae is related to water quality

4.What would be the best title for the passage?

A．Scientists Listen to Plants to Find Water Pollution

B．A Prototype Tester Is Used to Determine Water Pollution

C．The Importance of Photosynthesis of the Algae

D．The Problem of Chemical and Radioactive Carbon Testing

To extinguish (熄灭) different kinds of fires, several types of fire extinguishers have been invented. They must be ready for immediate use when fire breaks out. Most portable (手提式的) kinds operate for less than a minute, so they are useful only on small fires. The law requires（要求） ships, trains, buses and planes to carry extinguishers.

Since fuel, oxygen and heat must be present in order for fire to exist, one or more of these things must be removed or reduced to put out a fire. If the heat is reduced by cooling the material below a certain temperature, the fire goes out. The cooling method is the most common way to put out a fire. Water is the best cooling material because it is low in cost and easy to get.

Another method of extinguishing fire is by cutting off the oxygen. This is usually done by covering the fire with sand, steam or some other things. A blanket may be used to cover a small fire.

A third method is called separation, which includes removing the fuel, or material easy to burn from a fire, so that it can find no fuel.

The method that is used to put out a fire depends on the type of fire. Fires have been grouped in three classes. Fires in wood, paper, cloth and the like are called Class A fires. These materials usually help keep the fire on. Such fires can be stopped most readily by cooling with water.

1.If a fire breaks out on a bus, which of the following should be ready there for you to use?

A．Sand

B．Water

C． A blanket.

D．An extinguisher.

2.To cover a small piece of burning wood with a basin( 盆）in order to stop the fire is an example of___________.

A．separating the fire	B．reducing the heat
C．removing the fuel	D．cutting off the oxygen

3.In choosing how to put out a fire, we should first be clear about__________.

A．when it breaks out	B．how it comes about
C．what kind it is	D．where it takes place

4.What would the author probably discuss in the paragraph that follows?

A．Another class of fires	B．Another type of extinguishers
C．How fires break out.	D．How fires can be prevented.

To extinguish (熄灭) different kinds of fires, several types of fire extinguishers have been invented. They must be ready for immediate use when fire breaks out. Most portable (手提式的) kinds operate for less than a minute, so they are useful only on small fires. The law requires ships, trains, buses and planes to carry extinguishers.

Since fuel, oxygen (氧气) and heat must be present in order for fire to exist, one or more of these things must be removed or reduced to extinguish a fire. If the heat is reduced by cooling the material below a certain temperature, the fire goes out. The cooling method is the most common way to put out a fire. Water is the best cooling material because it is low in cost and easy to get.

Another method of extinguishing fire is by cutting off the oxygen. This is usually done by covering the fire with sand, steam or some other things. A blanket may be used do cover a small fire.

A third method is called separation, which includes removing the fuel, or material easy to burn, from a fire, so that it can find no fuel.

The method that is used to put out a fire depends upon the type of fire. Fires have been grouped in three classes. Fires in wood, paper, cloth and the like are called Class A fires. These materials usually help keep the fire on. Such fires can be stopped most readily by cooling with water.

1.If a fire breaks out on a bus, which of the follow should be ready there for you to use?

A. Sand B. Water

C. A blanket. D. An extinguisher.

2.To cover a small piece of burning wood with a basin in order to stop the fire is an example of .

A. separating the fire B. reducing the heat

C. removing the fuel D. cutting off the oxygen

3.In choosing how to put out a fire, we should first be clear about .

A. when it breaks out B. how it comes about

C. what kind it is D. where it takes place

4.What would the author probably discuss in the paragraph that follows?

A. Another class of fires B. Another type of extinguishers

C. How fires break out. D. How fires can be prevented.

The surprising experiment I am about to describe proves that air is all around you and that it proves down upon you. Air pressure is a wonderful force. When you swim underwater, you can feel water push down your body. The air all around you does the same. However, your body is so used to it that you do not notice this. The pressure is caused by a layer of air called the atmosphere. This layer surrounds the Earth, extending to about five kilometers above the Earth’s surface.

The following experiment is an easy one that you can do at home. But make sure that you are supervised, because you will need to use matches. Now foe the experiment！

What you need

·A hard-boiled egg without the shell

·A bottle with a neck slightly smaller than the egg

·A piece of paper

·A match

Metheod

1） Check that the paper will sit firmly on the neck of the bottle.

2） Tear the paper into strips and put the strips into the bottle.

3） Light the paper by dropping a burning match into the bottle.

4） Quickly sit the egg on the neck of the bottle.

Result

Astonishingly, the egg will be sucked into the bottle. Your friends will be amazed when you show them the experiment. But be careful when you handle matches.

Why it happened

As the paper burns, it needs oxygen and uses up the oxygen （air） in the bottle. The egg acts as a seal in the neck of the bottle, so no more air can get inside. This reduces the air pressure inside the bottle. The air pressure must equalize, so more air from outside must enter the bottle. The outside air pressure against the egg and then the egg is pushed into the bottle! The proves that air is all around and that it is pressing down on it.

1.Why is there the need to take care when you are doing the experiment?

A. The bottle could break.

B. You need to light the paper with a match.

C. The egg needs to be shelled.

D. The egg has to be perfectly placed on the neck of the bottle.

2.In the experiment, the burning inside the bottle can___.

A. equalize the air pressure inside and outside

B. make a seal in the neck of the bottle

C. finish up the oxygen inside the bottle

D. produce more oxygen inside the bottle

3.How did the egg put into the bottle？

A. The oxygen inside the bottle sucked the egg in.

B. It became salt without the shell.

C. The neck of the bottle was wide enough.

D. The outside air pressure forced it into the bottle.

4.The experiment is carried cut to prove ______.

A. water pushes on your body when you swim underwater.

B. the earth is surrounded by a layer of air called the atmosphere.

C. the pressure of air around us has a powerful force.

D. the air pressure is not equalized around us.

The oxygen equipment made it possible for the climbers to rest and sleep at very high ________．

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