有一读者问这样一句话：
(1)I asked for the letter to be sent to the school.
如何分析这里的to be sent to the school?
for the letter to be sent to the school是不定式复合结构，在此用作谓语动词asked的宾语。如作内部分析，for无意义，是一虚词；the letter是逻辑主语；to be sent to the school是一不定式短语，用作逻辑谓语。如将the letter看做asked for的宾语，to be sent to the school就是宾语letter的补足语。
你可能对“for+名（代）词+主动不定式”结构比较熟悉，如：
(2)It's for you to decide.
(3)She nodded for me to follow her.
而对“for+名（代）词+被动不定式”结构有点陌生，其实这种结构并不罕见，再如：
(4)She asked for the passage to be explained once again.
(5)What I want is for the case to be settled out of court.
(6)It was a simple request for a porter to be sent to his room.
(7)She heard him yell for a car to be brought.
