Active and passive voice

In an active sentence the subject does the action: ⟦The dog chased the cat.⟧ In a passive sentence the subject has the action done to it: ⟦The cat was chased by the dog.⟧ The passive is a form of ⟦be⟧ + the past participle. We use it when the doer is unknown or unimportant, or to put the focus on what happened.

Key facts

  • Active → passive: the object moves to the front, add ⟦be⟧ + the past participle, and the doer goes after ⟦by⟧.
  • Past: ⟦was⟧ / ⟦were⟧ + participle: ⟦The roof was damaged.⟧ ⟦The keys were found.⟧ Present: ⟦is⟧ / ⟦are⟧: ⟦The meals are cooked by the chef.⟧
  • The verb ⟦be⟧ agrees with the new subject: ⟦The trees were planted⟧ (plural), ⟦The tree was planted⟧ (singular).
  • Irregular participles: ⟦written⟧, ⟦seen⟧, ⟦broken⟧, ⟦eaten⟧, ⟦built⟧, ⟦caught⟧, ⟦blown⟧.
  • Leave out ⟦by …⟧ when the doer doesn't matter: ⟦The school was built in 1990.⟧ Science reports and news often use the passive.

Worked examples

Example 1

Make it passive: ⟦Thandi wrote the poem.⟧

  1. Move the object to the front: ⟦The poem⟧.
  2. Past, one thing: ⟦was⟧ + the participle of ⟦write⟧: ⟦was written⟧.
  3. Add the doer with ⟦by⟧: ⟦The poem was written by Thandi.⟧

Answer: ⟦The poem was written by Thandi.⟧

Example 2

Active or passive? ⟦The thieves were caught by the police.⟧

  1. The subject is ⟦The thieves⟧, but the police do the catching.
  2. ⟦were caught⟧ = ⟦be⟧ + participle: passive.

Answer: passive

Example 3

Make it active: ⟦The cars are built by robots.⟧

  1. The doer comes after ⟦by⟧: ⟦robots⟧.
  2. Make it the subject, with the present verb: ⟦Robots build the cars.⟧

Answer: ⟦Robots build the cars.⟧