[填空题]Scientists find that on our planet earthquakes are much more frequent where the plates ______.

[填空题]Scientists find that on our planet earthquakes are much more frequent where the plates ______.

[简答题]Other scientists believe that our search hasn’t been long enough to rule out the possibility that intelligent life exists in our galaxy.

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In July 1994 Jupiter, the largest planet in our solar system, was struck by 21 pieces of a comet (慧星). When the fragments (碎片) landed in the southern part of the giant planet, the explosions were watched by scientists here on earth. But what if our own planet was hit by a comet
The year is 2094. It has been announced that a comet is heading towards the Earth. Most of it will miss our planet, but two fragments will probably hit the southern part of the Earth. The news has caused panic.
On 17 July, a fragment four kilometers wide enters the Earth’s atmosphere with a huge explosion. About half of the fragment is destroyed. But the major part survives and hits the South Atlantic at 200 times the speed of sound. The sea boils and an enormous wave is created and spreads. The wall of water rushes towards southern Africa at 800 kilometres an hour. Cities On the African coast are totally destroyed and millions of people are drowned. The wave moves into the Indian Oce
A. The whole world becomes extremely cold.
B. All the coastal cities in Africa are destroyed.
C. The whole mankind becomes extinct.
D. The visit of the comet results in wars.

[简答题]Many scientists believe that our species ____________(有朝一日会濒临灭绝).

[填空题]Scientists can predict earthquakes by means of paying attention to places where pieces of the earth’ s surface meet or by ______.

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Scientists find that hardworking people live longer than average men and women. Career women (职业女性) are healthier than housewives. Evidence shows that the jobless are in poorer health than the job-holders. An investigation (调查) shows that whenever the unemployment rate increases by 1%, the death rate increases by 2%. All these seem to support one point: work is helpful to health.
Why is work good for health It is because work keeps people busy, away from loneliness. Researches show that people feel unhappy and worried when they have nothing to do. Instead, the happiest are those who are busy. Many high achievers who love their careers feel that they’re happiest when they are working hard. Work serves as a bridge between man and reality. By work, people come into contact with each other. By collective (集体的) activity, they find friendship and warmth. This is helpful to health. The loss of work means the los

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