问题
选择题
Wind power is an ancient source of energy ____ we may retum in the near future.[ ]
A. on which
B. by which
C. to which
D. from which
答案
答案：C
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Wind power is an ancient source of energy ____ we may retum in the near future.[ ]
A. on which
B. by which
C. to which
D. from which
答案：C