Typical defining relative clause with 'that' or 'which' as object

The shed has begun to rot We built itin the garden last year The shed (that/which) we built in the garden last yearhas begun to rot

Typical non-defining relative clause with 'which' as object

Which must be used in non-defining clauses; that is not possible: The shed in our garden has lasted for a long time. My father built itmany years ago

The shed in our garden, which my father built many years ago,has lasted for a long time

Relative pronoun object of a preposition: people

When we wish to refer to a person, only whom (not that) can be used directly after a preposition. In this position, whom cannot be omitted and cannot be reduced to who or be replaced by that. This use is formal and rare in everyday speech: He is the man to whom Igave the money

The preposition can be moved to the end-position. If this happens, it is usual in speech to reduce whom to who; it is also possible to replace who(m) bythat: She is the woman whom(or who, or that) I gave the money to

However, the most usual practice in informal style, when the preposition is in the end-position, is to drop the relative pronoun altogether, but only in definingclauses:

They are the people I gave the money to

There's hardly anybody he s afraid of

1.35.1 Typical defining relative clause with a preposition That person is the manager I complained to himThe person to whom I complainedis the manager The person who(m)/that I complained tois the manager The person I complained tois the manager

The complex sentence relative pronouns and clauses

Typical non-defining relative clause with a preposition

Who(m) must be used in non-defining clauses: that is not possible: The hotel manager refunded part of our bill I complained to himabout the service

The hotel manager, to whom I complained(or who(m) I complained to) about the service, refunded part of our bill

Relative pronoun object of a preposition: things/animals

When we wish to refer to things or animals, only which (not that) can be used directly after a preposition. When used in this way, which cannot be omitted. This use is formal and rare in speech:

This is the pan in whichI boiled the milk The preposition can be moved to the end-position. If this happens, it is possible to replace which by that:

This is the pan that(or which) I boiled the milk inHowever, the relative is usually dropped altogether when the preposition is in the end-position, but only in definingclauses:

This is the pan I boiled the milk in

These are the cats I gave the milk to