煤炭不是问题所在，问题在于我们如何使用它。解决方案在于更清洁的技术和更好的利用。

A person who is too nice an observer of the business of the crowd, like one who is too curious in observing the labor of bees, will often be stung for his curiosity.

数学之美在于它能够如此精确地描述宇宙。