22. Relative Clauses

Overview

Relative clauses are subordinate clauses that attach descriptive meaning to nouns and pronouns within a sentence. By embedding one clause inside another, speakers and writers can pack more information into a single, well-formed sentence. Knowing which relative pronoun or adverb to use—and when commas are required—is fundamental to accurate, fluent English. This chapter covers the full set of relative pronouns and adverbs, the defining versus non-defining distinction, omission rules, and preposition placement.

Definition

A relative clause is a subordinate, adjective-like clause that gives further detail about a noun or pronoun already mentioned in the sentence. It is introduced by a relative pronoun such as who, whom, which, that, or whose, or by a relative adverb such as where, when, or why, which anchors the clause to the noun it describes. Relative clauses fall into two broad categories: those that are essential to identifying the noun they modify, and those that merely supply additional, non-essential information about it.

Key Rules

  1. 1. Choosing the Correct Relative Pronoun (Who, Whom, Which, That)

    Select 'who' when the relative pronoun is the subject of the clause and refers to a person. Use 'whom' when it is the object of the verb or of a preposition and refers to a person. For animals and things, 'which' is the standard choice. The pronoun 'that' can substitute for 'who' or 'which' in defining (restrictive) clauses but is never used in non-defining clauses.

    Show example Example

    The engineer who designed this bridge spent over a decade refining the blueprints.

  2. 2. Expressing Possession with Whose

    Use 'whose' to indicate that something belongs to or is closely associated with the noun being modified. Unlike other relative pronouns, 'whose' can apply to people, animals, and inanimate objects alike, standing in place of possessive forms such as his, her, its, or their.

    Show example Example

    The researcher whose findings overturned the previous theory received international recognition.

  3. 3. Defining Clauses versus Non-Defining Clauses

    A defining (restrictive) clause identifies which specific person or thing is meant; it is written without commas and may use 'that.' A non-defining (non-restrictive) clause adds bonus information about a noun already clearly identified; it is set off by commas and must use 'who,' 'whom,' or 'which'—never 'that.'

    Show example Example

    The novel, which topped the bestseller list for six months, was adapted into a film.

  4. 4. Using Where and When as Relative Adverbs

    Use 'where' to link a clause to a noun denoting a place, and 'when' to link a clause to a noun denoting a period or moment in time. In formal registers, both can be replaced by a preposition followed by 'which' (e.g., 'in which' for 'when,' 'at which' for 'where').

    Show example Example

    The conference hall where the summit was held can accommodate over two thousand delegates.

  5. 5. Omitting the Relative Pronoun

    A relative pronoun may be left out only inside a defining clause and only when it serves as the grammatical object of the relative clause—not when it is the subject. Dropping a subject relative pronoun always produces an ungrammatical sentence.

    Show example Example

    The documentary she recommended last week finally arrived on the streaming platform.

  6. 6. Preposition Placement in Relative Clauses

    A preposition governing the relative pronoun can either precede the pronoun (the formal pattern) or appear at the end of the clause (the informal pattern). When the preposition is moved to the front, 'whom' must follow for people and 'which' for things; neither 'who' nor 'that' is acceptable in that position.

    Show example Example

    The committee on which she served for three years published its final recommendations last spring.

Example Sentences

  1. Example 1

    The historian who lectured at the symposium has published eleven books on ancient civilizations.

    Why this works

    Illustrates 'who' as the subject relative pronoun referring to a person in a defining clause.

  2. Example 2

    The old clock tower, which has stood in the town square for two centuries, is being restored.

    Why this works

    Illustrates a non-defining clause with commas and 'which' supplying extra information about an object.

  3. Example 3

    The stadium where the final was played holds over eighty thousand spectators.

    Why this works

    Illustrates the relative adverb 'where' connecting the clause to a place noun.

  4. Example 4

    The candidate whose proposal received the highest score will advance to the next round.

    Why this works

    Illustrates 'whose' expressing possession with a person as the antecedent.

Common Errors

  • The doctor which treated me was very professional.

    The doctor who treated me was very professional.

  • My apartment, that is located on the third floor, has a great view.

    My apartment, which is located on the third floor, has a great view.

  • The colleague whom I sent the email to her yesterday is on vacation.

    The colleague whom I sent the email to yesterday is on vacation.

  • I still remember the day where we won the championship.

    I still remember the day when we won the championship.

Key Takeaways

  • Use 'who' (subject) or 'whom' (object) for people, 'which' for things and animals, and 'that' as an alternative in defining clauses only.
  • Use 'whose' to express possession for people, animals, and objects alike.
  • Defining clauses identify the noun, require no commas, and may use 'that'; non-defining clauses add extra information, require commas, and cannot use 'that'.
  • Use 'where' to relate a clause to a place noun, 'when' to a time noun, and 'why' to a reason noun.
  • Omit the relative pronoun only in defining clauses where it serves as the grammatical object, never when it is the subject.
  • When a preposition precedes the relative pronoun, use 'whom' for people and 'which' for things; 'who' and 'that' are unacceptable in that position.
  • Never include a redundant pronoun (such as 'him', 'her', or 'them') later in the same relative clause.

Practice - Set 1

  1. The musician _____ violin was damaged in transit has cancelled her performance.

  2. The city _____ we spent our summer vacation is famous for its museums.

  3. The supervisor, to _____ you must submit your weekly report, is out of the office today.

  4. The smartphone _____ I purchased yesterday has an excellent camera.

  5. Autumn is the season _____ the leaves on the maple trees turn vibrant red.

  6. My new bicycle, _____ cost me a month's salary, was stolen from the garage.

  7. The mechanic _____ repaired my car did a fantastic job.

Practice - Set 2

  1. The reason _____ she declined the promotion remains a mystery to her colleagues.

  2. Select the sentence that contains a correctly punctuated non-defining relative clause.

  3. The driver _____ licence had expired was issued a heavy fine by the police officer.

  4. Identify the sentence in which the relative pronoun is correctly omitted.

  5. The village _____ my grandparents were born no longer exists on modern maps.

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