Jack didn't know where he could find his mother变为简单句

Jack didn't know where he could find his mother变为简单句

Jack didn't know where to find his mother.

where he could ----------where to

Jack can't find (out) his mother
其实原句konw 和 where 之间省略了that 。这是一个定语从句～
^_^个人观点，仅供参考～

应该是 Jack didn't find his mother anywhere。