Tips & Tricks: Voices

Theory

Voice is a grammatical feature of verbs that shows whether the sentence places more emphasis on the subject (the doer) or on the action/receiver. In other words, voice indicates whether the subject performs the action (active voice) or receives the action (passive voice).

In any sentence the subject is the person, thing, action or place the sentence is about; the object (when present) is the receiver of the action. Voice changes affect which of these is placed as the sentence subject and how the verb is formed.

Types

• Active Voice
  The subject (doer) is emphasised. The typical order is Subject + Verb + Object. Example: Rita writes a letter. (Rita = subject/doer; writes = verb; a letter = object/receiver.)
• Passive Voice
  The object or receiver is emphasised; the original object becomes the subject of the passive sentence. Passive sentences are formed with an appropriate form of the verb be + the past participle of the main verb. The doer can be introduced by by, or omitted if unimportant or unknown. Example: A letter is written by Rita. (A letter = subject/receiver; is written = be + past participle; by Rita = agent.)

Rules

• Basic structure
  Active: Doer / Actor + Verb + Object / Receiver. Passive: Object (becomes subject) + appropriate form of be + past participle + (by + doer).
• Past participle
  Passive voice always uses the past participle of the main verb. Regular verbs form this with -ed. Irregular verbs have forms such as -en, -t, -d, -n (for example, write → written, buy → bought).
• Helping verb (form of be)
  A form of be is required in every passive sentence and it changes according to tense and number. The correct form must agree with the passive subject.
• Tense-wise patterns (common)
  Present simple: is / am / are + past participle. Past simple: was / were + past participle. Present continuous: is / am / are being + past participle. Past continuous: was / were being + past participle. Present perfect: has / have been + past participle. Past perfect: had been + past participle. Future (will): will be + past participle. Modals: modal + be + past participle (for example, can be done, should be seen).
• Only transitive verbs
  Only verbs that take an object (transitive verbs) can be used in the passive voice. Intransitive verbs (for example, arrive, sleep, die) do not take an object and therefore normally cannot form a passive.
• Subject-verb agreement
  After conversion, ensure the new subject (former object) agrees in number with the auxiliary be. Example: The books were read by the students. (books = plural → were).
• Pronoun changes
  When a pronoun becomes the subject in passive voice, change its case accordingly: they saw me → I was seen by them. (me → I as subject; they → them as agent in the by-phrase).

How to convert quickly: step-by-step trick

• Find the object in the active sentence - this will become the subject in the passive sentence.
• Choose the correct form of be to match the tense and number of the new subject.
• Use the past participle of the main verb.
• Add the by-phrase if the doer (agent) is needed. Otherwise omit it for brevity or when the agent is unknown/irrelevant.
• Check pronoun forms and subject-verb agreement.
• Mnemonic: O - BE - PP (Object becomes subject; BE form; Past Participle).

Common pitfalls and quick checks for accuracy

• Do not attempt passive with intransitive verbs (for example, do not convert He arrived to passive).
• Remember to change pronoun cases when they move to subject position.
• Ensure the auxiliary be matches tense and number of the new subject - this is the most frequent error in conversions.
• If the agent is not mentioned in the active sentence, you must not invent one in the passive. Omit the by-phrase when unnecessary.
• When the active subject is a compound or long noun phrase, the by-phrase may be omitted to keep the sentence natural: The decision was taken.
• For exam questions, quickly identify the verb's tense in the active sentence before choosing the passive form; this prevents incorrect auxiliary selection.

Solved Examples

Below are practise and test items. Attempt them first, then check methods and answers.