they haven't decided where to go next?为什么不是they haven't decided where go to next?

they haven't decided where to go next?为什么不是they haven't decided where go to next?
they haven't decided where to go next?为什么不是they haven't decided where go to next?

they haven't decided where to go next?为什么不是they haven't decided where go to next?
where to go next做了haven't decided 的宾语,是名词性质的,to go 是非谓语动词形式；而where go 中的go是谓语动词形式,故错误.

动词不定式 to go 作decide的复合宾语
类似的还有比如：tell (sb) what to do；show (sb) how to cut the rice 等等

这是疑问词的不定式，即：疑问词+to do ，这一用法是固定的，它不像句子那样长且复杂。