Wind power is an ancient source of energy we may return in the near future.
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on which
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by which
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to which
D
from which
推荐题目
—When did your brother begin to show his interest in medicine.—It was a Saturday _____ he noticed his classmate experimenting on a frog in the lab.
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that
B
what
C
when
D
which
The time _________ I first spend with Nelson Mandela was a very difficult period of my life.
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when
B
which
C
of which
D
at which
—Do you have anything to say for yourselves?—Yes，there is one point________ we must insist on.
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A
why
B
where
C
how
D
/