学习数学的唯一方法就是做数学。
The only way to learn mathematics is to do mathematics.
Half the world is composed of people who have something to say and can't, and the other half who have nothing to say and keep on saying it.
我们不是从祖先那里继承地球；我们是从子孙那里借来的——这在林业中尤其如此。