如果你没有深陷其中，你怎么知道自己有多高？

I think that the more you know about life, the less you need to explain in a film.

Courtesy costs nothing. Lower the toilet seat after use. Let the people in the elevator exit before you enter. Return shopping carts to their designated areas. When you borrow something， return it better shape (filled up， cleaned) than when you got it.

"The human heart is a mystery, even to itself."

数学家的工作永无止境；总有更多的问题需要解决。