这是数着别人契上的齿数，而以为自己很富有。 

The measure of a good book is whether it makes you think, feel, and see the world differently.

I'm not afraid of others saying I'm not good enough, I'm afraid that I'm not good enough myself.

成功辨识的关键是找到一个足够灵活的模型结构，以捕捉系统的基本特征，同时又足够简单，可以从现有数据中估计出来。