Scientists say it may be five years ______ it is possible to test this medicine on human patients．
#31988
A
since
B
until
C
before
D
when
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_____ you keep on working hard, I don’t mind whether you get good marks in your class.
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A
As long as
B
As soon as
C
As well as
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as far as
I think you could complain, _______, of course, you are happy with the way thing s are.
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A
which
B
that
C
unless
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How can you expect him to make any progress ________ you never give him a chance to have a try?
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A
when
B
unless
C
even though
D
until