When can you omit "that", "which", or "who"?


There are two different situations where you can omit the relative pronouns thatwho, or which in English.

  1. When thatwho, or which is the object of the clause, we can leave out the relative pronoun.

    The book that I'm reading is fascinating.

    The book I'm reading is fascinating.

    The subject of the relative clause ("that I'm reading") is "I", and the relative pronoun "that" (the book) functions as the object of the clause.

    Look at this sentence.

    The waiter who served us yesterday was rude.

    The subject of the relative clause is who (the waiter), so we cannot leave out the relative pronoun. However, we can omit it in another way (see step 2).

    The waiter served us yesterday was rude.

  2. When the relative pronoun is the subject, we can omit thatwho, or which in two basic ways:
    • If thatwho, or which is followed by the verb "be" (in any form), both elements can be omitted.

      The keys that are on the table are mine.

      The keys on the table are mine.

    • If thatwho, or which is followed by a verb, both elements (pronoun and verb) can be changed into "-ing" form of the verb.

      People who follow healthy diets tend to live longer.

      People following healthy diets tend to live longer.

Some Examples 

  • I like the dress you bought last week.
  • I can't remember the name of the movie I watched on Sunday.
  • The chocolate you bought yesterday is too sweet.
  • I've just found the wallet I had lost yesterday.
  • The shirt I want is too expensive.
  • The girl I met yesterday is really cute.
  • The woman I was sitting next to on the bus was constantly invading my space.
  • Some of the people you invited didn't come.
  • The computer your brother bought is running slow.

Adapted from www.pristineword.com