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
[C] the ones
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____.
7.The earth is one of nine planets which move in____round the sun.
8.In August 1977， a satellite was____to gather data about the black holes in the Milky way.
9.The terms we would normally use to describe a scientific phenomenon are____here.
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