(2014·河南豫北三校联考)________is well known to everyone，I should say，is that a man becomes learned by asking questions.
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A
Who
B
It
C
As
D
What
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Humans are destroying nature day by day, ________, of course, will cause punishment sooner or later.
#32518
A
that
B
/
C
which
D
What
English differs from Spanish in ______ it is not pronounced as it is written.
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A
what
B
that
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this
D
which
you can borrow my car you promise not to drive too fast.
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A
unless
B
even if
C
in case
D
as long as
Robert failed to complete his education____ he found it hard to focus on his studies.
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A
although
B
if
C
because
D
while
Shall Mary come to the concert with us？－Not she has finished her paper．
#80489
A
since
B
once
C
when
D
unless