No one knows exactly when our ancestors started talking,but new evidence suggests  _______might have happened a long time ago.
#4852
A
which
B
what
C
it
D
they
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 The days we look forward to ____at last. 
#4624
A
comes
B
to come
C
came
D
coming
If you keep_____,you can sit on _____side of the boat.
#4670
A
quite,either
B
still,either
C
calm,each
D
silent,both
He is_______to have come back from the abroad.
#4799
A
possibly
B
possible
C
probable
D
likely