The best way to learn mathematics is to do mathematics.
The stories of our people are the stories of the land, and they are one and the same.
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 present state of the system of nature is evidently a resultant of what it was in the preceding moment, and if we conceive of an intelligence which at a given instant comprehends all the relations of the entities of this universe, it could state the respective positions, motions, and general effects of all these entities at any time in the past or future.