人生是不断选择的过程。

The present is the past rolled up for action, and the past is the present unrolled for understanding.

"The past is a foreign country; they do things differently there."

数学不仅仅是关于数字、方程、计算或算法：它是关于理解的。

可持续性不仅仅是一个流行词，更是我们的责任。

Perhaps as important is the relation between the existence of solutions to a competitive equilibrium and the problems of normative or welfare economics.