4.In some binary systems， astronomers have shown that there is an invisible companion star， a 'partner' to____which we can see in the sky.

　　[A] the one

　　[B] that

　　[C] the ones

　　[D] those

　　5.On the other hand， scientists have suggested that very advanced technology could one day____the energy of black holes for mankind.

　　[A] make fun of

　　[B] make sure of

　　[C] make use of

　　[D] make sense of

　　6.Astronomers have evidence of a few other stars too， which might have black holes as____.

　　[A] companies

　　[B] comparisons

　　[C] compounds

　　[D] companions

　　7.The earth is one of nine planets which move in____round the sun.

　　[A] track

　　[B] orbit

　　[C] tour

　　[D] route

　　8.In August 1977， a satellite was____to gather data about the black holes in the Milky way.

　　[A] posted

　　[B] delivered

　　[C] launched

　　[D] transmitted

　　9.The terms we would normally use to describe a scientific phenomenon are____here.

　　[A] inadequate

　　[B] invisible

　　[C] intense

　　[D] individual

　　10.We know nothing about events which happen once objects pass this boundary， But____，matter must behave very differently inside the hole.

　　[A] in addition

　　[B] in person

　　[C] in detail

　　[D] in theory