介系詞在關係子句的位置

關係子句常會出現介系詞，而關係代名詞是該介系詞的受詞。在口頭上，介系詞通常放在關係子句的句尾，關係代名詞可以省略。在正式英語上，介系詞會放在關係代名詞前，而關係代名詞不得省略。在以下例句中，寫在括號內的關係代名詞表示可以省略。

口頭英語	正式英語
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.