How can the object become subject in passive voice?

Active: I am writing a letter.
Passive: A letter is being written by me.

In this example a letter becomes the subject but letter is not doer of the verb so how can we say it is the subject?

So I want to know that in passive voice object become real subject or just comes on the position of subject.

  • "Subject" in this context is a syntactic attribute, so unquestionably a letter is the subject of the verb is. The "thematic role" distinction you're thinking of is agent (the "actor", as opposed to the patient, who undergoes the effects of an action). Commented Sep 19, 2022 at 11:25
  • 2
    "but letter is not doer of the verb" - in a way, it is. The main verb of the sentence is now to be ("is"), not to write ("written").
    – stangdon
    Commented Sep 19, 2022 at 11:33
  • Then who is the subject for verb write and what is the object for verb write in passive
    – Hadman
    Commented Sep 19, 2022 at 16:16
  • @Hadman The subject of "written" is understood as "I". There is no object in the passive of your particular example.
    – BillJ
    Commented Sep 19, 2022 at 16:50
  • @Hadman In the sentence "A letter is being written by me", the subject of the sentence is "a letter". There is no subject for the verb "write", because "written" is a past participle.
    – stangdon
    Commented Sep 21, 2022 at 17:16

1 Answer 1


You are mixing up grammar and semantics.

There is the grammatical subject. This is the "noun phrase that goes before the verb". The grammatical subject in the passive sentence "The letter is being written by me" is the noun phrase "the letter".

There is the grammatical object. The is the noun phrase that follows the verb. In the active sentence "I am writing the letter", the noun phrase "the letter" is an object, and the subject is "I".

Then there is the semantic role. For example the "agent", "beneficiary" or "patient". An "agent" is the thing (or person) that carries out an action. A "patient" is (in semantics) the thing (or person) that is affected by an event or that undergoes an event. There are lots more semantic roles.

In an active sentence, the semantic role of "agent" is indicated by the grammatical "subject", and the semantic role of "patient" is usually the grammatical object.

In a passive sentence the "patient" is the grammatical subject, and the "agent" is indicated by the optional "by ..." prepositional phrase.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .