Millions of stars are traveling about in space．A few form groups which journey together, but most of them travel alone．
And they travel through a universe so large that one star seldom comes near to another．For the most part each star makes its journey in complete loneliness, like a ship on an empty ocean．The ship well be well over a million miles from its nearest neighbor．From this it is easy to understand why a star seldom finds another anywhere near it．
We believe, however, that some two thousand million years ago, another star wandering through space, happened to come near our sun．Just as the sun and the moon raise tides(潮汐) on the earth, so this star must have raised tides on the surface of the sun．But they were very different from the small tides that are raised in our oceans; a large tidal wave must have traveled over the surface of the sun, at last forming a mountain so high that we cannot imagine it．As the cause of the disturbance came nearer, so the mountain rose higher and higher．And before the star began to move away again, its tidal pull had become so powerful that this mountain was torn to pieces and threw off small parts of itself into space．These small pieces have been going round the sun ever since．They are the planets．
(1)
Some two thousand million years ago, the mountain on the sun was raised probably because ________．
[ ]
A．
a large tidal wave of a star traveled over the surface of the sun．
B．
another star happened to come near the sun．
C．
the sun and the moon raised the tides on the earth．
D．
the star moved away from the sun．
(2)
The article suggests that ________．
[ ]
A．
our earth exists before the sun．
B．
how space formed．
C．
no one knows where the earth comes from．
D．
our earth used to be one part of a high mountain on the sun．
(3)
The expression”the cause of the disturbance”refers to ________．
[ ]
A．
the large tidal wave．
B．
the powerful tidal pull．
C．
the star coming near the sun．
D．
one of the sun planets．
(4)
In this article, the writer mainly wants to tell the readers ________．
[ ]
A．
that the universe is so large that we cannot imagine it．
B．
how the high mountains were formed on the sun．
C．
why the tides over the surface of the sun were so powerful
