数学思想的真正考验是它能否激发进一步的思考。
The true test of a mathematical idea is its ability to inspire further thought.
The great advantage of old age is that you can be as rude as you like.
你想用卖糖水来度过余生，还是想要一个机会来改变世界？
效率是以正确的方式做事，而效能则是做正确的事。