Recent research has claimed that an excess of positive ions in the air can have an ill effect on people’s physical or psychological health. What are positive ions? Well, the air is full of ions, electrically charged particles, and generally there is a rough balance between the positive and the negative charged. But sometimes this balance becomes disturbed and a larger proportion of positive ions are found. This happens naturally before thunderstorm, earthquakes when winds such as the Mistral, Hamsin or Sharav are blowing in certain countries. Or it can be caused by a build-up of static electricity indoors from carpets or clothing made of man-made fibres, or from TV sets, duplicators or computer display screens.
When a large number of positive ions are present in the air many people experience unpleasant effects such as headaches, fatigue, irritability, and some sensitive people suffer nausea or even mental disturbance. Animals are also affected, particularly before earthquakes, snakes have been observed to come out of hibernation, rats to flee from their burrows, dogs howl and cats jump about unaccountably. This has led the US Geographical Survey to fund a network of volunteers to watch animals in an effort to foresee such disasters before they hit vulnerable areas such as California.
Conversely, when large numbers of negative ions are present, then people have a feeling of well-being. Natural conditions that produce these large amounts are near the sea, close to waterfalls or fountains, or in any place where water is sprayed, or forms a spray. This probably accounts for the beneficial effect of a holiday by the sea, or in the mountains with tumbling streams or waterfalls.
To increase the supply of negative ions indoors, some scientists recommend the use of ionisers: small portable machines, which generate negative ions. They claim that ionisers not only clean and refresh the air but also improve the health of people sensitive to excess positive ions. Of course, there are the detractors, other scientists, who dismiss such claims and are skeptical about negative/positive ion research. Therefore people can only make up their own minds by observing the effects on themselves, or on others, of a negative rich or poor environment. After all it is debatable whether depending on seismic readings to anticipate earthquakes is more effective than watching the cat.
1.What effect does exceeding positive ionization have on some people?
A.They think they are insane.
B.They feel rather bad-tempered and short-fussed.
C.They become violently sick.
D.They are too tired to do anything.
2.In accordance with the passage, static electricity can be caused by___.
A.using home-made electrical goods.
B.wearing clothes made of natural materials.
C.walking on artificial floor coverings.
D.copying TV programs on a computer.
3.A high negative ion count is likely to be found___.
A.near a pound with a water pump.
B.close to a slow-flowing river.
C.high in some barren mountains.
D.by a rotating water sprinkler.
4.What kind of machine can generate negative ions indoors?
A.Ionisers.
B.Air-conditioners.
C.Exhaust-fans
D.Vacuum pumps.
5.Some scientists believe that___.
A.watching animals to anticipate earthquakes is more effective than depending on seismography.
B.the unusual behavior of animals cannot be trusted.
C.neither watching nor using seismographs is reliable.
D.earthquake
BCDAA
暂无解析
Theauthortellsusinparagraph4________.
Passage 4
Questions 16 to 20 are based on the following passage:
The new global satellite communications systems will offer three kinds service, which may overlap in many different kinds of receivers.
VOICE. Satellite telephones will be able to make calls from anywhere on the Earth to anywhere else. That could make them especially useful to remote, third world villages (some of which already use stationary satellite telephones), explorers and disaster-relief teams. Today’s mobile telephones depend on earth-bound transmitters, where technical standards vary from country to country. So business travelers cannot use their mobile phones on international trips. Satellite telephones would make that possible.
MESSAGING. Satellite massagers have the same global coverage as satellite telephones, but carry text alone, which could be useful for those with laptop computers. Equipped with a small screen like today’s papers, satellite massagers will also receive short messages.
TRACKING. Voice and messaging systems will also tell their users where they are to within a few hundred meters. Combined with the messaging service, the location service could help rescue teams to find stranded adventurers, the police to find stolen cars, exporters to follow the progress of cargoes, and haulage companies to check that drivers are not detouring the pub. America’s military Global Positioning System (GPS) satellite will provide better positioning information to anyone who has a receiver for their signals, but GPS does not carry messages, so such a receiver cannot be used on its own for tracking or rescue. By the mid-1990s, GPS receivers will be able to tell people where they are to within 70 meters anywhere in the world, and to within a meter or so in areas where the service is supplemented by ground-based transmitter.
16. Global satellite communications systems will be useful to .
A. laptop computer users
B. remote villages
C. disaster-relief teams
D. all above
17. Satellite telephone will make .
A. business travelers use mobile phones on international trips
B. possible calls from anywhere on earth to anywhere else
C. explorers happy
D. all above
18. Which of the following is true?
A. The positioning precision of the voice system is better than that of GPS.
B. The positioning precision of GPS is Better than that of the voice system.
C. The positioning precision of the messaging system is better than of GPS.
D. The positioning precision of voice system is better than that of the messaging system.
19. What can we say about the new global satellite communications systems?
A. They are widely used.
B. They are very helpful.
C. They are costly.
D. Both A and B.
20. Which of the following may be the best title for the passage?
A. Global Satellite Communications
B. New Voice and Messaging System
C. New Generation Satellite
D. Always in Touch
PartIVTranslation
Asthesourceofaluminumisalmostinexhaustible,wecanexpectthatmoreandmoreuseswillbefoundforthisversatilemetal.(PassageTwo)
The first paragraph is intended to ________.