1.这个收缩的过程如此强烈，以至于黑洞产生了。

　　2.直到最近天文学家们才开始研究黑洞。

　　3.但是从理论上说，物质在黑洞里的行为一定非常不同。

　　4.黑洞最强有力的证据来自对双星系的研究。

　　5.有一天也许人类也会遭此命运。

　　单元自测答案 Unit 2

　　Ⅰ Word Spelling

　　1.density 2.collapse 3.boundary

　　4.constant 5.basis 6.launch

　　7.twin 8.companion 9.mankind

　　10.speculation 11.swallow 12.inadequate

　　13.matter 14.circumstance 15.occur

　　16.intense 17.evidence 18.invisible

　　19.astronaut 20.tropical

　　Ⅱ Word Form

　　1.were reported 2.having 3.made

　　4.believed 5.is being pulled 6.swallowing

　　7.convincing 8.totally 9.consists

　　10.coloured

　　Ⅲ  Vocabulary and Structure

　　1.B 2.D 3.A 4.A 5.C

　　6.D 7.B 8.C 9.A 10.D

　　Ⅳ  C-E Translation

　　1.This process of shrinking is so intense that a black hole results.

　　2.It is only recently/It is not until recently that astronomers have begun specific research into black holes.

　　3.But in theory， matter must behave very differently/in a very different manner inside the black hole.

　　4.The most convincing evidence of black holes comes from research into binary star systems.

　　5.Mankind may one day meet this fate.