1.Which came first, black holes or galaxies?
是先有黑洞呢？还是先有星系？
2.Without it, galaxies and clusters of galaxies should fly apart.
如果没有，星系及星系群应该会分崩离析。
3.They turned their telescopes toward other nearby galaxies.
他们把望远镜转向附近的其他星系。
4.Large galaxies grow by eating small ones.
大星系靠吃掉小星系来成长。
5.Over billions of years, the gas was compressed by gravity into galaxies, stars, plants and eventually, even humans.
在数十亿年的时间里，这些气体被引力压缩成星系、恒星、植物，最终甚至变成了人类。
6.Until recently most astronomers believed that the space between the galaxies in our universe was a near-perfect vacuum.
直到最近，大多数天文学家都认为我们宇宙中星系之间的空间是近乎完美的真空。
7.Recent findings lend strong support to the theory that a black hole lies at the center of the Milky Way and of many of the 100 billion other galaxies estimated to exist in the universe.
最近的发现有力地支持了这样一种理论，即银河系中心，和宇宙中估计存在的1000亿个其他星系中的许多里有一个黑洞。