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反過來，始終反過來：把情況或問題顛倒過來，從反面看。

廣東話諺語

Sustainability is not a choice anymore—it's our responsibility to future generations.

Society can and does execute its own mandates， and if it issues wrong mandates instead of right， or any mandates at all in things with which it ought not to meddle， it practices a social tyranny more formidable than many kinds of political oppression， since， though not usually upheld by such extreme penalties， it leaves fewer means of escape， penetrating much more deeply into the details of life， and enslaving the soul itself.

數學不僅僅是一系列抽象概念的集合，而是一種讓我們理解宇宙的語言。