Only when his mother died how much he loved his mother.
A. he realised
B. did he realise
C. he had realised
D. had he realised
网友回答
A. he realised
(答案→)B. did he realise
C. he had realised
D. had he realised
解析： 考查倒装句。only +状语放在句首时，使用部分倒装，从句不倒装，主句倒装，根据语境时态应用过去式，故选B。