wind power is an ancient source of energine _____we may return in the near future

问题描述:

wind power is an ancient source of energine _____we may return in the near future
关系词怎么填写

此题考察定语从句,先行词是energy,从句we may return in the near future,这里动词有一个搭配 即return to
A B两个选项中的介词不能和return搭配.which 指代energy.
=Wind power is an ancient source of energy which we may return to in the near future.
所以答案是: to which