I didn’t know how would they go to london.

I didn’t know how would they go to london.
I didn’t know how would they go to london.

I didn’t know how would they go to london.
I didn’t know how they would go to london

不对 应该是 I didn't know how they would go to London。
宾语从句要用陈述语序
有不明白的地方再问哟，祝你学习进步，更上一层楼！ (*^__^*)

不对

对

应该这样做：I didn’t know how they would go to london。
因为how they would go to london是从句，从句不要用疑问句句式哦，所以would不能放到 they前面来。

这个 有些语法错误
前面是一般过去时 后面又是完成时 有点混乱
I didn’t know how they go to london