I have no idea where the girl could have gone to.为什么不可以+to?

I have no idea where the girl could have gone to.为什么不可以+to?
I have no idea where the girl could have gone to.为什么不可以+to?

I have no idea where the girl could have gone to.为什么不可以+to?
idea后是定语从句where the girl could have gone 正常句式应该是 the girl could have gone where 所以where前不加to