电磁场的方程是从实验事实中推导出来的。

The end of history will be a very sad time. The struggle for recognition, the willingness to risk one's life for a purely abstract goal, the worldwide ideological struggle that called forth daring, courage, imagination, and idealism, will be replaced by economic calculation, the endless solving of technical problems, environmental concerns, and the satisfaction of sophisticated consumer demands.

我们相信多元化的能源未来，多种能源共同满足全球需求。

可持续的森林是既能支持野生动物又能维持生计的森林。

"The biggest risk is not taking any risk."

Art is contemplation. It is the pleasure of the mind which searches into nature and which there divines the spirit of which nature herself is animated.