Using proper verbs in Results subheadings instead of abstract nouns can improve the understanding of the results obtained.

Under proper conditions, sound waves will be reflected from a hillside or other such obstruction. Sound travels at the rate of about one-fifth of a mile per second. If the hill is eleven hundred feet away, it takes two seconds for the sound to travel to the hill and back. Thus, by timing the interval between a sound and its reflection (the echo) , you can estimate the distance to an obstruction.

During World War II the British used a practical application of this principle to detect German planes on their way to bomb London long before the enemy was near the target. They used radio waves instead of sound waves, since radio waves can penetrate fog and clouds. The outnumbered Royal Air Force(RAF) always seemed to the puzzled Germans to by lying in wait at the right time and never to be surprised. It was radio echoes more than anything else that won the Battle of Britain.

Since the radio waves were used to tell the direction in which to send the RAF planes and the distance to send them (their rage of flight, in other words) , the device was called "radio directing and ranging" , and from the initials the word "radar" was coined.

Sound waves reflected from a hill can be used to estimate the______.

A．height of the hill

B．speed of sound

C．distance to the hill

D．intensity of sound

Under proper conditions, sound waves will be reflected from a hillside or other such obstruction. Sound travels at the rate of about one-fifth of a mile per second. If the hill is eleven hundred feet away, it takes two seconds for the sound to travel to the hill and back. Thus, by timing the interval between a sound and its reflection (the echo) , you can estimate the distance to an obstruction.

During World War II the British used a practical application of this principle to detect German planes on their way to bomb London long before the enemy was near the target. They used radio waves instead of sound waves, since radio waves can penetrate fog and clouds. The outnumbered Royal Air Force(RAF) always seemed to the puzzled Germans to by lying in wait at the right time and never to be surprised. It was radio echoes more than anything else that won the Battle of Britain.

Since the radio waves were used to tell the direction in which to send the RAF planes and the distance to send them (their rage of flight, in other words) , the device was called "radio directing and ranging" , and from the initials the word "radar" was coined.

Sound waves reflected from a hill can be used to estimate the______.

A．height of the hill

B．speed of sound

C．distance to the hill

D．intensity of sound

Automotive accidents are one of the leading causes of death in children. Child safety advocates argue that harsh penalties should be imposed on drivers who fail to place children under 30 pounds in rear-facing children's seats in the rear of the car whenever a car is in motion. Such penalties, they argue, will help save children's lives. All of the following statements support the argument of the child safety advocates EXCEPT:

A．The rear seats of a car are safer for all passengers, both adults and children, in the event of an accident.

B．Studies have shown that children in rear-facing seats have been shown to sustain less serious injuries in accidents than children in front-facing seats.

C．Studies have shown that children under 30 pounds can sustain serious injuries in even minor accidents if they are not properly restrained.

D．Studies have shown that children between 60 and 90 pounds are safest in a car when using both a seat belt and a properly sized booster seat.

E．Some drivers will not abide by regulations unless they are forced to do so by the threat of harsh penalties.

听力原文： In many stressful situations, the body's responses can improve our performance. We become more energetic, more alert, better able to take effective action. But when stress is encountered continually, the body's reactions are more likely to be harmful than helpful to us. The continual speeding up of bodily reactions and production of stress-related hormones seem to make people more susceptible to heart disease. And stress reactions can reduce the disease fighting effectiveness of the body's immune system, thereby increasing susceptibility to illnesses ranging from colds to cancer.

Stress may also contribute to disease in less direct ways by influencing moods and behavior. People under stress may become anxious or depressed, and as a result may cat too much or too little, have sleep difficulties or fail to exercise. These behavioral changes may in turn be harmful to their health. In addition, people are more likely to pay attention to certain bodily sensations such as aches and pains when they are under stress and to think that they're sick. If the person were not under stress, the same bodily sensations might not be perceived as symptoms and the person might continue to feel well.

Some researchers have suggested that assuming the role of a sick person is one way in which certain people try to cope with stress. Instead of dealing with the stressful situation directly, these people fall sick. After all, it is often more acceptably in our Society to be sick and to seek medical help than it is to admit that one cannot cope with the stresses of life.

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A．Their performance may improve.

B．Their immune system may be reinforced

C．Their blood pressure may rise all of a sudden.

D．Their physical development may be enhanced.

To improve reading speed, people can scan some unnecessary explanations and examples.

A．Y

B．N

C．NG

Farmers can improve agricultural production by using more and more expensive fertilizers to make the degraded land get enough nutrients.

A．Y

B．N

C．NG

A good reader is very much like a driver. He must change his reading speed to fit his purpose and the material he is reading, just as a driver does to fit the road situation (情况). A good reader may be able to read a thousand words per minute (WPM), but he won't use that speed for everything he reads. A good reader doing research (研究) reading in the library may read at the speed of 1,000 words per minute as he looks for materials for a report. But once he finds something that is useful to him he may need to slow down to 100 WPM. A good reader may read newspaper and magazine articles at 600 WPM, but it may take him 150 WPM to read his science or maths text. A driver has a wide change of speed, so has a good reader.

According to the writer, good readers can ______ .

A．often go to the library

B．read at 1,000 WPM

C．change the speed as needed

Spam messages are increasing rapidly and are soon expected to make up about half of all email messages. Using【70】______methods, spammers can send millions of emails with the click of a button. Anti-spammers struggle to keep up with their tactics, using trained technicians and software filters to minimise spam. Internet service【71】______are leading the fight against spam, which costs them and their customers billions of dollars each year. Anti-spam technicians watch the flow of email on the Internet, keeping an eve out for mass mailings. However, spammers are hard to track, since they can easily【72】______in the web of technology. Some small companies are trying to fight spam by collecting the email addresses of spam senders and publicizing them. Individuals can slow spam too, by【73】______chat groups, choosing a longer email address, and keeping multiple accounts. Still, in the long run, it may take new【74】______ or stricter laws to stop spam. In the meantime, users will continue【75】______under huge quantities of spam.

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