题目内容

　 Microwaves are usually used to warm up food, but what about warming people?

Using microwaves to directly heat owners of a room would save much of the energy wasted by heating walls and furniture. And despite popular ideas about microwaves, this technique would be safe, according to Charles R. Burlier of the Microwave Research Center in Marlborough, New Hampshire. Low-power microwaves only penetrate (贯穿) the skin (low-power microwave penetration in a ham is about 0.2 inches, for example) and with no negative effects.

　 To test this idea, Buffler subjected himself to microwaves in a special room using a standard 500-watt, 2459 MHz magnetron (磁控管). He found that a person will start to feel warmth at about 20 milliwatts per square centimeter (mw. / sq. cm.) ; a satisfactory feeling of warmth occurs between 35 and 50mw. / sq. cm. By comparison, a person standing in noonday summer sun feels the amount of 85 mw. / sq. cm. And a frozen meat pie in your microwave oven receives about 1000 mw. / sq. cm.

　 In houses of the future, each room could be provided with its own magnetron, says Buffler. When you stepped into the living room, for example, a motion detector would turn on the magnetron, filling the room with low-power microwaves. In the same way that a microwave oven heats up a hamburger, but not the plate it’s on, you would feel warmth from the microwaves without changing the temperature of your coffee table. (You could, however, make your favorite easy chair even more comfortable by treating it with a radiation-absorbing chemical. )

　 While it might be some time before homeowners are comfortable enough with the idea to set up whole-body microwave heaters in houses, Buffler says microwaves may attract livestock farmers. Lambs that are born outdoors in winter, for example, are frequently lost to cold. Microwaves could warm the lambs safely and quickly.

76. Which of the following can tell the main idea of the passage?

A. A new heating system.　　　　　　　　 B. A new microwave oven.

C. A popular technique. D. The magnetron.

77. According to paragraph 2, which of the following does not describe the characteristics of a microwave heater?

A. It directly heats people in a room　　　　 B. It heats walls and furniture in a room.

C. It is safe.　　　　　　　　　　　　 　　D. It saves energy．

78. The test conducted by Buffler shows that when a person feels comfortable warmth, he receives about______.

A. 20 mw. / sq. cm.　　　 B. 40 mw. / sq. cm.　 C. 60 mw. / sq. cm. 　 D. 85 mw. / sq. cm

79. According to paragraph 4, which of the following fills the room with low-power microwaves?

A. The magnetron.　　　　　　　　　　　　 B. A frozen meat pie.

C. The microwave oven.　　　　　　　　　 D. The radiation-absorbing chemical.

80. Which of the following statements about microwave heaters would Buffler most probably agree with?

A. Microwave heaters will soon be widely used by homeowners.

B. Microwave heaters sometimes make people feel uncomfortable.

C. Perhaps microwave heaters will be first used by livestock farmers, who wish to protect their lambs in winter.

D. Microwave heaters cannot be accepted by the public because they are somewhat unsafe.

ABBAC

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阅读理解

　　Microwaves that transmit television signals always travel in a straight line. Because the earth is round, it is impossible to send television signals over a long distance. For example, if we tried to send television signals directly from Europe to America, the microwaves carrying the signals would shoot into space over the Atlantic and would reach America.

　　If we want to send television signals around the surface of the earth, we must send them from point to point by the relay system. On land we can set up relay stations for this purpose, and we can pass signals from station to station in a series of straight lines. However, we can not do this so easily over water. In order to send pictures directly across the Atlantic, for example, we would need to build a chain of relay stations across the ocean, which is about 3,000 miles wide. One choice would be to build one great tower in the middle of the ocean. But the tower would have to be 500 miles high!

　　Both of the ideas are impossible. So we use the communication satellite thousands of miles in outer space to relay the television signals across the Atlantic. A satellite receives the picture signals in a straight line from the ground station on one side of the Atlantic, from England, for example. Then it sends signals down again, also in a straight line, to the ground station on the other side of the Atlantic in the United States. The communication satellite must be within view of both ground stations at the same time.

1．What are microwaves?

[　　]

A．They are light waves that are useless.

B．They are radiation which can travel straight.

C．They are not waves.

D．They are very short waves used in TV and radar.

2．Why should people build relay stations?

[　　]

A．Because the microwaves can not travel a long time.

B．Because the microwaves are strong enough to reach another place.

C．Because the microwaves travel in a straight line and the earth is round.

D．Because people want to show their power.

3．Television signals must be sent

[　　]

A．from city to city

B．from point to point

C．from house to house

D．from building to building

4．What's the main reason for us to use satellites to relay TV programmes?

[　　]

A．Satellites can cover large areas.

B．We can't build relay stations on the land.

C．Satellites are cheaper.

D．Using the satellites, we can receive only a few programmes.

阅读理解

　　Microwave cooking is probably the best cooking discovery besides fire．In fact, it might be better than fire, since microwaves, instead of a flame or an electric element, cook the food．

　　Microwaves are short radio waves, similar to heat and light waves．They work by movement．They cause the molecules(分子)in food to move, which produces friction(摩擦力)．(It’s similar to rubbing your hands together when they’re cold．)The friction produces heat in the food(not in the oven), and the heat cooks the food．

　　There is a legend behind the use of microwaves for cooking．

　　Percy Le Spencer was employed by the Raytheon Company during the World War Ⅱ．One day on 1942 he was working with magnetrons(电磁管), which can produce microwaves．When he pulled a candy bar from his pocket, it was a melted mess．Although Spencer was working on scientific experiments, not trying to invent a new way of cooking, he realized that it was the microwaves that had melted the candy．Spencer knew that if microwaves melted candy, they would cook other foods as well．The Raytheon Company agreed, and in 1947 it introduced its Radarange to the public．

　　The first ovens were suspected(怀疑)of causing health problems, but the new models were safe when the factory’s instructions were followed．Microwave cooking now can be found in many homes all over the world．

(1)

Microwaves cook food by ________．

[　　]

A．

producing fire

B．

producing electricity

C．

giving off heat

D．

causing the molecules to move

(2)

Microwave cooking is a great invention made ________．

[　　]

A．

after countless experiments

B．

by chance

C．

by the Raytheon Company in 1942

D．

by Spencer in 1947

(3)

According to the passage, which is TRUE about how microwaves cook food?

[　　]

A．

Microwaves can produce heat to cook the food．

B．

Microwaves cause food to move so as to produce heat to cook it．

C．

Microwaves rub the food so as to produce heat to cook it．

D．

Microwaves cause molecules in food to move, which produces friction that produces heat in food to cook it．

(4)

What does this passage mainly talk about?

[　　]

A．

An invention discovered by mistake．

B．

Microwave cooking．

C．

How microwaves cook food．

D．

The invention of the first microwave oven．

阅读理解

　　Microwaves may be great at warming up food, but what about warming people?

　　Using microwaves to directly heat owners of a room would save much of the energy wasted by heating walls and furniture．And despite popular ideas about microwaves, this technique would be safe, according to Charles R．Burlier of the Microwave Research Center in Marlborough, New Hampshire．Low-power microwaves only penetrate(贯穿)the skin(low-power microwave penetration in a ham is about 0．2 inches, for example)and with no negative effects．

　　To test this idea, Buffler subjected himself to microwaves in a special room using a standard 500-watt, 2459 MHz magnetron(磁控管)．He found that a person will start to feel warmth at about 20 milliwatts per square centimeter(mw./sq.cm.); a satisfactory feeling of warmth occurs between 35 and 50mw．/sq.cm. By comparison, a person standing in noonday summer sun feels the amount of 85 mw．/sq.cm. And a frozen meat pie in your microwave oven receives about 1000 mw．/sq.cm.

　　In houses of the future, each room could be provided with its own magnetron, says Buffler．When you stepped into the living room, for example, a motion detector(运动感应器)would turn on the magnetron, filling the room with low-power microwaves．In the same way that a microwave oven heats up a hamburger, but not the plate it’s on, you would feel warmth from the microwaves without changing the temperature of your coffee table．(You could, however, make your favorite easy chair even more comfortable by treating it with a radiation-absorbing chemical．)

　　While it might be some time before homeowners are comfortable enough with the idea to set up whole-body microwave heaters in houses, Buffler says microwaves may attract livestock(家畜)farmers．Lambs that are born outdoors in winter, for example, are frequently lost to cold．Microwaves could warm the lambs safely and quickly．

(1)

Which of the following can tell the main idea of the passage?

[　　]

A．

A new heating system．

B．

A new microwave oven．

C．

A popular technique．

D．

The magnetron．

(2)

According to paragraph 2, which of the following does not describe the characteristics of a microwave heater?

[　　]

A．

It directly heats people in a room．

B．

It heats walls and furniture in a room．

C．

It is safe．

D．

It saves energy．

(3)

The test conducted by Buffler shows that when a person feels comfortable warmth, he receives about ________．

[　　]

A．

20 mw．/sq.cm.

B．

40 mw．/sq.cm.

C．

60 mw．/sq.cm.

D．

85 mw．/sq.cm.

(4)

According to paragraph 4, which of the following fills the room with low-power microwaves?

[　　]

A．

The magnetron．

B．

The motion detector．

C．

The microwave oven．

D．

The radiation-absorbing chemical．

(5)

Which of the following statements about microwave heaters would Buffler most probably agree with?

[　　]

A．

Microwave heaters will soon be widely used by homeowners．

B．

Microwave heaters sometimes make people feel uncomfortable．

C．

Perhaps microwave heaters will be first used by livestock farmers, who wish to protect their lambs in winter．

D．

Microwave heaters cannot be accepted by the public because they are somewhat unsafe．

阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项。

　　Microwaves may be great at warming up food, but what about warming people?

　　Using microwaves to directly heat owners of a room would save much of the energy wasted by heating walls and furniture．And despite popular ideas about microwaves, this technique would be safe, according to Charles T．Burlier of the Microwave Research Centre in Marlborough, New Hampshire．Low-power microwaves only penetrate(贯穿)the skin(low-power microwave penetration in a ham is about 0.2 inches, for example)and with no negative effects．

　　To test this idea, Buffer subjected himself to microwaves in a special room using a standard 500-watt, 2459 MHz magnetron(磁控管)．He found that a person would start to feel warmth at about 20 milliwatts per square centimeter(mw．/sq．cm．)； a satisfactory feeling of warmth occurs between 35 and 50 mw．/sq．cm．By comparison, a person standing in noonday summer sun feels the amount of 85 mw．sq．cm．And a frozen meat pie in your microwave oven receives about 1000mw．/sq．cm．

　　In houses of the future, each room could be provided with its own magnetron, says Buffler．When you stepped into the living room, for example, a motion detector would turn on the magnetron, filling the room with low-power microwaves．In the same way that a microwave oven heats up a hamburger, but not the plate it's on, you would feel warmth from the microwaves without changing the temperature of your coffee table．

　　While it might be some time before homeowners are comfortable enough with the idea to set up whole-body microwave heaters in houses, Buffler says microwaves may attract livestock(家畜)farmers．Lambs that are born outdoors in winter, for example, are frequently lost to cold．Microwaves could warm the lambs safely and quickly．

(1)

Which of the following can tell the main idea of the passage?

[　　]

A．

A new heating system．

B．

A new microwave oven．

C．

A popular technique．

D．

The magnetron．

(2)

According to the paragraph 2, which of the following does not describe the characteristics(特点；特征)of a microwaves heater?

[　　]

A．

It directly heats people in a room．

B．

It heats walls and furniture in a room．

C．

It is safe．

D．

It saves energy．

(3)

The test conducted by Buffler shows that when a person feels comfortable warmth, he receives about ________．

[　　]

A．

20 mw．/sq．cm

B．

40 mw．/sq．cm．

C．

60 mw．/sq．cm．

D．

85 mw．/sq．cm．

(4)

Which of the following statements about microwave heaters would Buffler most probably agree with?

[　　]

A．

Microwave heaters will soon be widely used by homeowners．

B．

Microwave heaters sometimes make people feel uncomfortable．

C．

Perhaps livestock farmers, who wish to protect their lambs in winter, will first use microwave heaters．

D．

The public will not accept microwave heaters because they are somewhat unsafe．

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