生活是一首歌，唱出来吧。

The reason that the invisible hand often seems invisible is that it is often not there.

从我巨大的悲伤中，我创作出我的小歌谣。

Profitability and responsibility must go hand in hand, or neither will last.

在数学中，提出问题的艺术必须比解决问题更有价值。