Here are some images of clusters of galaxies. 这是一些星团的照片。 They're exactly what they sound like. 正如听上去一样。 They are these huge collections of galaxies, 它们是一堆星系， bound together by their mutual gravity
A WORLD THAT STANDS AS ONE July 24, 2008 | Berlin, Germany Thank you to the citizens of Berlin and to the people of Germany. Let me thank Chancellor Merkel and Foreign Minister Steinmeier for welcomin
Remarks of President Barack Obama Weekly Address The White House September 19, 2009 Weekly Address: Progress in the Global Economy from White House on Vimeo. 演讲文本: Leaders of the world’s largest econo
