"The human heart is a mystery, even to itself."

No president who performs his duties faithfully and conscientiously can have any leisure.

Running a business requires long-term vision, not just immediate benefits.

引力比其他力弱得多这一事实可能是物理学中最深刻的谜团。

膨胀是一个非常大胆的想法，但它似乎是解释宇宙观测特征的唯一方法。