高等教育 / 新发展英语综合教程（二）
The reason why all the solar energy falling on the earth can't be utilized is that _ _ _ _ _ _ .
A、only a very small part is available
B、the sun is too distant from the earth
C、it takes thousands of years for this energy to be stored up in coal and oil
D、our scientific knowledge is not sufficient
A、only a very small part is available
B、the sun is too distant from the earth
C、it takes thousands of years for this energy to be stored up in coal and oil
D、our scientific knowledge is not sufficient
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