The discovery of stars orbiting the supermassive black hole at the galactic center was a turning point in astrophysics.
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。
Liberal democracy may constitute the "end point of mankind's ideological evolution" and the "final form of human government," and as such constituted the "end of history."
实现明天的唯一限制是我们今天的疑虑。
The strength of a nation lies in the unity of its people.
教室仍然是学院中最具可能性的激进空间。