In this experiment,they are woken up several times during the night,and asked to report what they_.

问题描述:

In this experiment,they are woken up several times during the night,and asked to report what they_.
A.had just been dreaming B.are just dreaming C.have just been dreaming D.had just dreamt
怎么不能选D

因为整句句子时态是现在进行时,之前当然是现在完成时.asked只是表示被动语态,跟时态无关.