正确答案: D

社会矛盾运动

题目：人类社会发展的根本动力是

查看原题 查看所有试题

学习资料的答案和解析：

[单选题]1948年12月30日，毛泽东在以下哪篇文章中首次公开使用“人民民主专政”的概念（　　）

《将革命进行到底》

解析：历史知识，要记住。

[单选题]From here, we can see the bridge ________ construction．

by

解析：Below在下面，under在……之下、在……情况中，by经过、在……之旁，with关于、由于。选项C是正确的。【句子大意】从这里我们可以看到正在修建中的大桥。

[单选题]The reason why all the solar energy falling on the earth can’t be utilized is that ______．

根据以下内容，回答下面的题目。The energy which the sun radiates goes in every direction, and only a minute part of it falls on the earth．Even so, it represents power of about 5,000,000 horsepower (马力) per square mile per day; the sun gives us as much energy every miunte as mankind utilizes in a year．At present, we use this energy indirectly, and it is our final source of power．Coal represents the chemical action of the sun on green plants thousands of years ago．Water power results from the rain formed by vapor which comes from the evaporation of water under the sunshine．Even windmills operate because of air currents set in motion by the different heating affects of the sun in different places．Some day, through chemistry or some type of solar engine, we shall harness this great source of energy more directly．Already a scientist has worked out an engine, surprisingly efficient, in which the sun’s rays are concentrated through mirrors on a tube of water to create steam．How much energy given off by the sun reaches the earth?

our scientific knowledge is not sufficient