问题
选择题
Only when I put myself in their position ________ they were more miserable than me.
A．I had known
B．had I known
C．I knew
D．did I know
答案
答案：D
句意：只有当我设身处地为他们想的时候，我才知道，他们比我更加痛苦。only＋状语从句位于句首时，主句要用部分倒装，know这个动作发生在put之后，所以不能用过去完成时，因此选D。