Mobile phones should carry a label if they proved to be a dangerous source of radiation, according to Robert Bell, a scientist. And no more mobile phone transmitter towers （发射塔） should be built until the long-term health effects of the radiation they emit （放射） is scientifically evaluated, he said. "Nobody's going to drop dead overnight but we should be asking for more scientific information," Robert Bell said at a conference on the health effects of low-level radiation. "If mobile phones are found to be dangerous, they should carry a warning label until proper shields can be devised," he said.
A report widely circulated （传播） among the public says that up to now scientists do not really know enough to guarantee there are no ill effects on humans from radiation. According to Robert Bell, there are 3.3 million mobile phones in Australia alone and they are increasing by 2,000 a day. By the year 2000 it is estimated that Australia will have 8 million mobile phones: nearly one for every two people.
As well, there are 2,000 transmitter towers around Australia, many in high density （密度） residential areas. For example, Telstra, Optus and Vodaphone build their towers where it is geographically suitable to them and disregard the need of the community. The radiation emitted from these towers may have already produced some harmful effects on the health of the residents nearby.
Robert Bell suggests that until more research is completed the government should ban construction of phone towers from within a 500 meter radius （半径） of school grounds, child care centers, hospitals, sports playing fields and residential areas with a high percentage of children. He says there is emerging evidence that children absorb low-level radiation at a rate more than three times that of adults. He adds that there is also evidence that if cancer sufferers are subjected to radiation the growth rate of the disease accelerates （提高）.
Robert Bell calls on the major telephone companies to fund adequate research and urges （敦促） the government. to set up a wide ranging inquiry into possible health effects.
31 According to Robert Bell, if mobile phones prove to be dangerous to people's health.
A they should be banned immediately.
B the use of them should be restricted.
C all transmitter towers should be torn down.
D a warning label should be attached.
32 How many mobile phone users will there be in Australia by the year 2000 according to the passage?
A 3.3 million.
B Almost half of the population.
C One third of the population.
D One fourth of the population.
33 Many transmitter towers were built
A on high mountains.
B in places suitable to the phone users.
C in areas which can take in radiation.
D in densely populated areas.
34 Who absorb low-level radiation at a higher rate than the others?
D Old people.
35 This article mainly argues that
A the government should restrict the number of mobile phone users.
B mobile phones may have ill effects on people.
C mobile phones have proved to be harmless to people's health.
D no more phone towers should be constructed.
A Thirsty World
The world is not only hungry, it is also thirsty for water. This may seem strange to you, since nearly 75% of the earth's surface is covered with water. But about 97% of this huge amount is sea-water, or salt water. Man can only drink and use the other 3% - the fresh water that comes from rivers, lakes, underground, and other sources. And we cannot even use all of that, because some of it is in the form of icebergs （冰山） and glaciers （冰川）. Even worse, some of it has been polluted.
At the moment, this small amount of fresh water is still enough for us. However, our need for water is increasing rapidly. Only if we take steps to deal with this problem now can we avoid a severe worldwide water shortage later on. A limited water supply would have a bad effect on agriculture and industry.
In addition to stopping wasting our precious water, one useful step we should take is to develop ways of reusing it. Experiments have already been done in this field, but only on a small scale.
Today, in most large cities, water is used only once and it eventually returns to the sea or runs into underground storage tanks. But it is possible to pipe water that has been used to a purifying （净化） plant. There it can be filtered （过滤） and treated with chemicals so that it can be used again just as if it were fresh from a spring.
But even if every large city purified and roused its water, we still would not have enough. Where could we turn next? To the oceans! All we'd have to do to make use of the vast amount of sea-water is - remove the salt. This salt-removing process is already in use in many parts of the world.
So if we take all these steps, we'll be in no danger of drying up!
36 The phrase "the world" in the first line of the passage refers to
37 What percentage of the earth's water can man actually use at present?
A Nearly 75 per cent.
B About 97 per cent.
C Exactly 3 per cent.
D Less than 3 per cent.
38 According to the passage, we can avoid a worldwide water shortage in the future by
A increasing rainfall.
B reusing water and utilizing sea-water.
C cutting down our consumption of water.
D reducing the number of factories producing steel.
39 Which of the following statements, according to the passage, is NOT true?
A A limited water supply will affect industrial production.
B Every large city purifies and reuses its water.
C Purified water is not exactly as fresh as spring water.
D Oceans are the largest water source.
40 According to the passage, sea-water can be turned into fresh water by
A heating it up.
B treating it with chemicals.
C taking salt out of it.
D drying it up.
Computers in Cars
You're far from home on a lonely road. Shadowy forests stretch away on both sides. A thick mist （雾） makes it difficult to see far beyond your car's windshield
"Can this be route 90A?" you wonder. If it is, you should be near a town. Yet there's no hint of one. Night is closing in. And you're low on gasoline.
This is a situation where an in, car computer that can navigate would be a big help.
A car computer that-navigates? Yes! Such computers exist. Several experimental models are being tested by General Motors, Ford, Chrysler, and several foreign car makers. These computers vary in detail. But they all contain series of maps on videodiscs or videotapes. For example, one computer system contains 13,300 maps covering the continental US.
Before starting out on a trip, a driver can type in the code for the region he or she plans to drive through. The computer then shows a map of that region. At the same time, a tiny radio receiver linked to the computer goes to work. It picks up signals from navigation satellites such as the NAVSTAR network. Using these signals, the computer shows 'the car's position at all times and displays this position on the map. The computer can also calculate and display the best route to follow.
A navigation computer may also receive and" use data about road construction, weather conditions, and traffic jams. This information would be displayed to the driver and the computer would also use the information to work out alternate （交替的） routes.
Most cars nowadays also contain computers that help cars run more efficiently. Microprocessors （微处理机） control certain engine functions by regulating the mixing of fuel. Data on car speed, oil pressure, revolutions per minute, engine temperature, and fuel level can be displayed as digital data （numbers） or warning lights.
Some auto designers suggest that a central computer display be used to clearly present such timely information as car speed and fuel level. Warning lights would indicate a drop in oil pressure or a sudden rise in engine temperature. To get more informatio6 On these conditions, the driver could call it up on the computer display screen. When needed, the computer could be "asked" to provide navigation aid or information about the car's condition.
41 By describing a typical situation of a lost driver on the road, the author intends to
A make us believe how complex the highway computer network is.
B let us know how in-car computers are linked to road signs.
C show us how helpful a navigation computer can be.
D tell us that NAVSTAR has come into use.
42 The word "navigate" in Paragraph 3 means
A "help one control the traffic".
B "help one find one's way".
C "give a ship correct information about its course".
D "direct a plane to its destination".
43 The navigation computers have one thing in common: they al
A contain series of maps on videodiscs or videotapes.
B contain 13,300 maps covering the continental US.
C can be obtained free of charge.
D cost a lot of money.
44 Without signals from navigation satellites, the in-car computer
A would still be able to locate the car's position at all times.
B would fail to locate the car's position.
C could still work out the best route to follow.
D would seek help from the radio receiver linked to it.
45 Of the following functions, which is NOT possessed by the navigation computer?
A Showing a map of the region a driver plans to drive through.
B Predicting a car crash on the road.
C Getting information about road construction, weather conditions, and traffic jams.
D Showing the car's position at all times and displaying it on the map.
31. D 32. B 33. D 34. A 35. B
36. A 37. D 38. B 39. B 40. C
41. C 42. B 43. A 44. B 45. B