Every possible means ________ to prevent the air pollution，but the sky is still not very clear.
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A
were using
B
have used
C
has been used
D
was used
推荐题目
The factory used 65 percent of the raw materials, the rest of which ________ saved for other purposes.
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A
is
B
are
C
was
D
were
“39 Steps”is one of the most exciting films_________ directed by my brother.
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A
which were
B
which was
C
that was
D
that were
Here _______a photo of my family. My family _______ in it.
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A
are, are
B
is, are
C
are, is
D
is, is