Sometimes people forget where they __ something.

问题描述:

Sometimes people forget where they __ something.
A.have put B.are putting C.has put D.will put

A 有时候人们会忘了他们把东西放在哪了.
因为从句中 put 时间发生在主句 forget 前,所以要用现在完成时.
they 是复数,所以用have,不用has