单项选择题

What do both theories assume to be true

A．That new material is continually being formed.
B．That, in time, the universe will contract.
C．That the universe is expanding at present.
D．That" a big bang" started the expansion.

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单项选择题

According to Lemaitre , the separate galaxies formed

A．during a pause in the expansion of the universe.
B．at the time of the primeval explosion.
C．and will continue to form for ever.
D．about 20, 000 million years ago.

单项选择题

We see distant galaxies as they were long ,long ago because

A．they were closer together then.
B．the universe has always looked as the same.
C．their light takes so long to reach us.
D．they have travelled such a long way.