“疑问词+动词不定式”结构可以改写成由该疑问词引导的从句

where
to
go
is
still
not
deteremined
it
is
still
not
deteremined
where
to
go
主要区别是主语不同第一个where
to
go疑问词+动词不定式作主语
第二个it指示代词作主语
他指代的就是where
to
go