Question

向各位高手请教一下关于英语的问题

Only then did he realize that he had lost.为什么不能吧其中的“did he realize”换成“did he realized”或者是“he realize”

Answer 1

Only then did he realize that he had lost..
only then 开头的句子要倒装，也就是要跟一般疑问句形式。
He realized that he had lost . 变一般疑问句就是 did he realize that he had lost.
过去时变一般疑问句要借助助动词did , 动词过去式变原形。

Answer 2

不能,前面有了did he,后面就必须用原形了,that后面是过去完成时.did he+v原形,因为你读读这句.
He realized that he had lost.这句可以.又因为Only开头,所以不完全倒装.
所以,我认为不能替换成你说的那两种.
本人高一,英语不行请多指教.

Answer 3

that引导的宾语从句用的是过去完成时、
所以、他意识到这件事的时候、应该用过去式。
只有前面用过去式、表示过去的过去才能用过去完成时。
而only句首、倒装句提前助动词did、后面就必须是原型。