For example in this sentence:
- "Your message was sent"
I think here sent is not the past form. It's an adjective right? Or isn't it?
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.Sign up to join this community
You are right! "sent" is not a past tense verb; it's a form of past participle. The past participle is needed in prototypical passive structure. The subject1 in your sentence is your message.
ACTIVE : Someonesubject sentpast tense verb your message
PASSIVE : Your messagesubject was sentpast participle by someone
In English passive structure, the by-phrase (by someone here) can be omitted if you think it's unimportant or if it's unknown. The passive structure with the by-phrase is called a long passive; the passive structure without the by-phrase is called a short passive.
1 The subject is not necessarily the doer of the action. See 5.1 subject and predictate
All sentences need subjects (except in some conversational English). The confusion lies in the difference between active and passive. The key difference isn't word form, it's the function.
In the active voice, the subject does the action, while in the passive voice, the subject receives the action.
Therefore, in this sentence:
You sent the message.
"You" is the subject, and does the action (sending the message).
However, in this sentence:
Your message was sent.
"Your message" is the subject, and it receives the action of sending. How do we know that "your message" is the subject? One simple way is to notice that it's before the verb. Remember that in English, the subject comes before the verb except in some poetry and really old literature. Another, more contextual, way you can identify the subject is by remembering that in the passive voice, the subject receives the action.