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If time travel is possible, where are the tourists from the future?

Sustainable development requires balancing economic growth with environmental protection.

"A book is a dream that you hold in your hands."

The unpredictable is the ground on which creativity flourishes.

伽羅瓦群和自守形式之間的聯(lián)系是數(shù)學中最深刻的奧秘之一。