密码学是关于在存在对手的情况下进行通信的。

The paper industry has a responsibility to lead the way in environmental stewardship.

"The only real failure in life is not to be true to the best one knows."

现实总是比小说更丰富、更复杂。

我们开采的每一桶石油都必须以最小的环境影响负责任地进行。