I wish I'd known about that rule earlier 其中'd是哪个单词?如题,would?had?

I wish I'd known about that rule earlier 其中'd是哪个单词?如题,would?had?
I wish I'd known about that rule earlier 其中'd是哪个单词?
如题,would?had?

I wish I'd known about that rule earlier 其中'd是哪个单词?如题,would?had?
had 注意known是过去分词.

had