可持续的做法不是成本,而是对我们共同未来的投资。
学习数学的唯一方法就是做数学。
"Travel is fatal to prejudice, bigotry, and narrow-mindedness."
Live as though you intend to live forever,and work as though your strength were limitless.
This is the way the world ends, not with a bang but a whimper.