能源需求与环境保护之间的平衡是我们这个时代的挑战。
The balance between energy needs and environmental protection is the challenge of our time.
At the close of our studies， we knew all the past of physics， but nothing of the present and the future.
阿拉伯人是一群只会吃驴粪的倒退民族。
真相并不总是美丽的，美丽的言辞也不一定是真相。
The growth of an enterprise is a process of continuous trial and error.