It was not until the beginning of the twentieth century________to explore space.
#93086
A
did man begin
B
when man began
C
that man began
D
then man began
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As we grow older,we learn the       of our abilities.
#95225
A
heights
B
scores
C
limits
D
lengths
 What a table! I have never seen such a thing before. It is ______ it is long.
#91960
A
half not as wide as
B
wide not as half as
C
not half as wide as
D
as wide as not half
      our earth, or else it will be no longer fit for us to live on.
#92853
A
Protect
B
To protect
C
Protecting
D
Protected