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“及物动词+副词”“及物动词+介词”以及“及物动词+副词+介词”构成的短语动词可用于被动结构。
At last they put out the fire. → At last the fire was put out.
Have you sent for a doctor? → Has the doctor been sent for?
My classmates caught up with me in this exam. → I was caught up with by my classmates in this exam.
许多“不及物动词+介词”以及“不及物动词+副词+介词”构成的短语动词相当于及物动词，也可以有宾语，也可用于被动结构。
The boys laughed at him for the foolish mistake. → He was laughed at for the foolish mistake.
They looked down on peasants in the old days. → Peasants were looked down on in the old days.
带有双宾语的句子在变为被动结构时，这两个宾语的任何一个都可作被动句的主语。
The teacher gave the student a new book. → The student was given a new book (by the teacher).
带有复合宾语的句子变为被动结构时，宾语补足语要相应变为主语补足语。
Everybody called her Big Sister. → She was called Big Sister (by everybody).
People last saw the lost girl playing near the river. → The lost girl was last seen playing near the river.
function n. 功能；作用；机能 vi. 起作用；正常工作；运转
function as 起……作用；具有……功能
function well/normally 运转良好/ 正常
perform/fulfill a...function履行……职责， 发挥……作用
perform a variety of functions履行多种职责
