单项选择题

"Greenhouse effect" means ______.

A．the way in which gases are used for keeping plants warm
B．a natural course which is to some degree helpful to us
C．the way" greenhouse gases trap heat on the earth
D．the whole course in which greenhouse gases prevent heat

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热门试题

单项选择题

If there were no greenhouse effect, ______.

A．no plants would grow on our planet
B．earth would be thirty degrees colder
C．man could not live on the earth
D．all of the above answers are correct

单项选择题

Suppose the earth's temperature rose by 3 degrees, ______.

A．great harm would be done to mankind
B．the sea level would go by 10 centimetres
C．all the land in the world would be flooded
D．crops would be unable to grow on the earth