He didn't know to choose which one.该为He didn't know which one to choose.求原因?one后为什么加to
问题描述：
He didn't know to choose which one.该为He didn't know which one to choose.求原因?one后为什么加to
答
know to do
答
to choose是不定式做one这个不定代词的后置定语啊
答
choose为动词,用to接动词,to choose为不定式作one这个不定代词的后置定语