采矿业必须发展以满足不断变化的世界的需求。

I'm the reason your brain won't think.

Work spares us from three evils: boredom， vice， and need.

Happiness ain't a thing in itself --- it's only a contrast with something that ain't pleasant. That's all it is.

农业的真正进步不仅以产量衡量成功，还要看生态系统健康。