发现恒星围绕银河系中心的超大质量黑洞运行是天体物理学的一个转折点。

The most important challenge facing the world today is the need to create strong, effective, and accountable states in the developing world.

The aim of every artist is to arrest motion, which is life, by artificial means and hold it fixed so that a hundred years later, when a stranger looks at it, it moves again since it is life.

网球给了我一切，我想回馈一些东西。