题目： [单选,材料题] 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
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发表于 2022-4-14 15:12:49
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发表于 2022-4-14 16:00:19
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