Why does she always ask you for help ---- There is no one else ( ),is there

题目

Why does she always ask you for help ---- There is no one else ( ),is there
A.who to turn to B.she can turn to
C.for whom to turn D.for her to turn
为什么呢,先行词是 no one else 那为什么A不行,其他呢

答案

turn to 求助于,to是介词
先行词是 one
she can turn to 是定语从句,省略了关系代词that/who,因为关系代词在从句中做turn to 的宾语
如果选A要把who去掉,这样就是不定式短语做后置定语,修饰one