Il y a souvent des prépositions dans les propositions relatives, et le pronom relatif est le complément d'objet de cette préposition. En anglais courant, la préposition est normalement placé à la fin de la proposition relative et le pronom relatif est facultatif. En anglais formel (surtout à l'écrit), la préposition est souvent placée avant le pronom relatif, et dans ce cas le pronom ne peut être omis. Dans les exemples ci-dessous, les pronoms entre parenthèses sont facultatifs.
Exemples
| Anglais courant | Anglais formel |
|---|---|
| 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. |