种树最好的时间是二十年前，其次是现在。
The best time to plant a tree was twenty years ago. The second best time is now.
In mathematics, the simplest explanation is often the most profound.
Every human being has an essential, inborn striving toward self-actualization.
我觉得布什总统根本没有为艾滋病做任何事。事实上，我都不能确定他会不会拼艾滋这个单词。