煤炭曾是工业进步的支柱，但其未来必须平衡经济需求与环境责任。
Coal has been the backbone of industrial progress, but its future must balance economic needs with environmental responsibility.
Theorems are the permanent literature of mathematics.
动作是完整思考过程的最后一部分，精神的提升必须借助于活动或工作。
后悔是我们喝下的毒药，却希望别人会死。