From paragraph 7 we know that_________.A、there is a new galaxy born once every two or three years
B、no new stars are thought to exist in the galaxy
C、no new stars will be observed in the future
D、all galaxies were born at the same time
【正确答案】：D
【题目解析】：细节判断题。题干要求细读第七段的内容。这一段主要简述了天体和星系的知识。大意是每年都有2到3颗新星出现在我们太阳系。但所有的星系几乎都诞生于同一时间。人们认为并不存在新的星系。A选项混淆了star和galaxy; B选项内容与文中内容矛盾；C选项与B选项一样在内容上与文章内容矛盾。只有D选项最符合原文，故而答案为D。