Active & Passive Voice

Voice tells us whether the subject of a sentence performs the action or receives the action. Understanding voice helps you write clearer sentences and recognise how meaning shifts when you rearrange who does what.

What You'll Learn

• How to identify whether a sentence is in the active voice or passive voice
• How to transform an active sentence into a passive sentence using the formula: subject + be + past participle + by + agent
• When the "by + agent" phrase can be left out
• How to choose the correct form of "be" (is, are, was, were) for present and past simple tenses

When to Use

1. When the action matters more than the doer: "The homework was collected by the monitor." (We care about the homework being collected.)
2. When the doer is unknown: "My wallet was stolen at the hawker centre." (We do not know who took it.)
3. When the doer is obvious: "The suspect was arrested last night." (It is obvious the police did it.)
4. When you want a formal or objective tone: "The results were announced during assembly." (Formal school setting.)
5. When writing about events in reports or news: "A new MRT station was opened in Punggol." (News-style writing.)

How to Form

The Active Voice Structure

In an active sentence, the subject performs the action on the object.

Subject + Verb + Object

• "The gardener waters the plants."
• "Priya painted the poster."

The Passive Voice Structure

In a passive sentence, the object of the active sentence becomes the subject. The doer moves to the end (or is dropped entirely).

Subject (receiver) + be + past participle + (by + agent)

• "The plants are watered by the gardener."
• "The poster was painted by Priya."

Step-by-Step Conversion

Choosing the Correct Form of "Be"

Key Rules

1. Only transitive verbs can become passive: A transitive verb has an object. "She ate the cake" can become passive because "the cake" is the object. "She slept" cannot become passive because there is no object.

2. Always use the past participle, not the past tense: Write "was eaten", not "was ate". Write "was written", not "was wrote". The past participle is the third form of the verb.

3. Match "be" to the new subject: If the new subject is singular, use "is" or "was". If it is plural, use "are" or "were". "The letter was sent." vs "The letters were sent."

4. Match "be" to the tense of the original verb: If the active sentence is in the present tense, use "is/are". If it is in the past tense, use "was/were".

5. "By + agent" is optional: Include the agent when it adds important information. "The novel was written by Roald Dahl." Omit it when the agent is unknown, unimportant, or obvious. "The window was broken." (We do not know who did it.)

6. Change object pronouns to subject pronouns: When the object pronoun moves to the front, it must change form. "The teacher praised him." becomes "He was praised by the teacher."

Common Mistakes

Clue Words

Signals that a sentence is passive:

was, were, is, are + past participle (e.g., was taken, is eaten, were sold, are made)

by + the person or thing that performed the action (e.g., by the teacher, by the wind)

Signals that a sentence is active:

The subject comes first and clearly performs the action. There is no "be + past participle" pattern.

Common irregular past participles to know:

eaten, written, broken, taken, given, made, built, sold, caught, stolen, chosen, drawn, spoken, thrown, worn

Tip: If you see "was/were + past participle" in a sentence, it is almost certainly in the passive voice. Look for the "be + V3" pattern!

Practice Tips

1. Use the swap test: Take any active sentence and try to move the object to the front. If you can add "was/were + past participle" and the sentence still makes sense, the verb is transitive and the sentence can be made passive.

2. Ask "who did the action?": In a passive sentence, the doer appears after "by" or is missing entirely. If the sentence does not clearly show who performed the action at the start, it may be passive.

3. Memorise irregular past participles: Many common verbs have irregular third forms (eat-ate-eaten, write-wrote-written). Keep a list of the ones you find tricky and review them regularly.

4. Check subject-verb agreement last: After converting to passive, always re-read the sentence to make sure "be" matches the new subject in number (singular/plural) and tense (present/past).

Quick Reference

Active vs Passive Formula

Common Verbs: Past Participle Forms