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  3. Recent research had claimed that an excess of positive ions in the air could

Recent research had claimed that an excess of positive ions in the air could

游客2023-07-18  30
问题     Recent research had claimed that an excess of positive ions in the air could 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.  If the balance becomes disturbed and a larger proportion of positive ions are found. This happens naturally before thunderstorms, earthquakes or when winds such as the Mistral, Foehn, 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 fibers, 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 particularly sensitive people suffer nausea or even mental disturbance.  Animals are also found to be affected, particularly before earth- quakes; 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 that 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 in 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. [br] By observing the behavior of animals, scientists may be able to _______.
选项 A、prevent disasters
B、organize groups of people
C、predict earthquakes
D、control areas of California
答案 C
解析 事实细节题。文章第一段第五句提到正离子过剩出现于灾难发生前夕，第二段第二、三句提到动物这时会有异常反应，所以科学家已经开始观察动物希望能预测灾难(in an effort to foresee such disasters)，所以C正确。
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