可持续林业不仅仅是砍伐树木,更是培育文明。
圆的周长大于任何内接等边多边形的周长,小于任何外切多边形的周长。
There is no such thing as society: there are individual men and women, and there are families.
好的悬疑故事应该让读者一直猜测到最后,但所有线索都必须存在。
The perfection of the work depends on the simplicity of the means.