(·上海)Wind power is an ancient source of energy we may return in the near future.A. on

问题补充：

(·上海)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

答案：

A. on which

B. by which

(答案→)C. to which

D. from which

解析：考查“介词＋which”引导的定语从句。表示“重新回到……上”要用return to。which替代的是先行词“an ancient source of energy”。句意：风能是一种古老的能源，在不久的将来我们可能要重新利用这种能源。