介词在关系子句的位置

关系子句常会出现介词，而关系代词是该介词的受词。在口头上，介词通常放在关系子句的句尾，关系代词可以省略。在正式英语上，介词会放在关系代词前，而关系代词不得省略。在以下例句中，写在括号内的关系代词表示可以省略。

口头英语	正式英语
Is that the man (who) she arrived with?	Is that the man with whom she arrived?
Does he know the girl (that) John is talking to?	Does he know the girl to whom John is talking?
The person (who) he is negotiating with is the Chairman of a large company.	The person with whom he is negotiating is the Chairman of a large company.
It is a club (which) many important people belong to.	It is a club to which many important people belong.
He liked the people (that) he lived with.	He liked the people with whom he lived.
The tree (that) they had their picnic under was the largest and oldest in the park.	The tree under which they had their picnic was the largest and oldest in the park.
It was the river (that) the children preferred to swim in.	It was the river in which the children preferred to swim.
The jungle (that) the tribe lived in was full of strange and unusual animals.	The jungle in which the tribe lived was full of strange and unusual animals.