单项选择题

Man has known that ______.

A．the Milky Way is the only galaxy
B．other galaxies are near ours
C．the sun is a large star in the Milky Way
D．the earth is a small part of the universe

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热门试题

单项选择题

In the Milky Way we can see many ______.

A．galaxies
B．suns like ours
C．stars like our sun
D．both B and C

单项选择题

We use ______ to work out how far a star is from us.

A．kilometres
B．metres
C．light-years
D．months and years