Relative clauses: identify or add detail

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A relative clause can identify a noun: the person who called; the room that we booked. A defining clause supplies information needed to identify the referent. A non-defining clause adds extra information and is separated by commas in writing.

Try the three exercise formats

Examples to compare

  • The person who called left a message.
  • This is the room we booked.
  • My bicycle, which is ten years old, still works.

Watch the meaning and the limits

Who can refer to people, which to things, and that to people or things in defining clauses. Do not use that to introduce an ordinary non-defining relative clause. When an object relative pronoun is omitted, keep the subject and verb: the room we booked.

Read each example aloud, then change one detail to make a sentence you could use. Continue with focused practice when you want a different set.

Common mistakes and how to fix them

Mistake: This is the room that we booked it.

Use: This is the room that we booked.

Room is already the object represented in the relative clause; do not repeat it as it.

Try the pattern

3 choose questions · 2 sentence completions · 2 word gaps. Read the reason after every answer. No timer.

Typed answers stay on this page. This guided set checks the requested construction; it does not judge general writing. Read the accepted answers and reasons.

Use it in your own sentence

Write one sentence about your own routine or situation. Check the subject, verb form and intended meaning against the rule above. A different sentence may need a different form: these exercises accept the reviewed answers for their stated context.

Try the next practice set, or choose another grammar point.

All drill answers and reasons

  1. The person ___ called left a message. Choose the person pronoun.

    Choices: who / which / where

    Accepted: who

    Who refers to a person and is the relative-clause subject.

  2. My bicycle, ___ is ten years old, still works.

    Choices: which / that / what

    Accepted: which

    Use which, not that, in this non-defining clause.

  3. Choose the grammatical defining clause.

    Choices: the room we booked / the room we booked it / the room booked we

    Accepted: the room we booked

    The object is represented by room; do not repeat it as it.

  4. Complete this defining clause, using book in the past: This is the room ___ . (subject: we; no extra object)

    Accepted: we booked / that we booked / which we booked

    The object relative pronoun can be omitted or stated as that or which.

  5. Complete this defining clause: The person ___ left a message. (called me; include a relative pronoun)

    Accepted: who called me / that called me

    Who and that both introduce this defining clause about a person.

  6. My bicycle, ___ is ten years old, still works. Use a relative pronoun.

    Accepted: which

    Which introduces this non-defining clause about a thing; that does not.

  7. The person ___ called left a message. Use who or that.

    Accepted: who / that

    Who and that can both introduce this defining subject relative clause.

Practice questions

How do the three exercise formats work?

Choose asks you to pick an answer. Complete the sentence asks you to type the missing phrase. Fill in the word asks for one word, or no article where stated. Every checked answer includes a reason.

Which typed answers are accepted?

Use the form and meaning requested in the prompt. Reviewed alternatives and contractions are accepted where they fit. Capital letters, surrounding spaces, straight or curly apostrophes and a final full stop, question mark or exclamation mark do not affect marking. The answer reference lists the accepted forms.

Are my typed answers sent or saved?

Typed answers stay on this page in your browser. They are not sent to the server or saved. If device progress is available, completing a set records only the activity and study points on this device.

Can this check my own writing or certify my level?

No. This is a small guided set with reviewed answers, not a general grammar checker or a level certificate. An unlisted answer does not mean it is always wrong in English. Read the prompt and the explanation for this construction.

Further reference: Cambridge English Grammar Today. The explanations, examples and exercises here are original; each lesson covers a useful pattern rather than every exception.