*66.Wind power is an ancient source of energy ______ we may return in the near future.
问题描述：
*66.Wind power is an ancient source of energy ______ we may return in the near future.
A.on which B.by which
C.to which D.from which
翻译并分析句子.
答
在不久的将来,我们也许会回归到风能这样一种古老的能量来源（对其加以利用）.
宾语从句which没问题,return介词短语介词前置于which前,根据句子意思,return to是正解.
希望对你有帮助~