"They were surprised by a knock at the door." is passive voice.
This
To change a sentence into passive the sentence must be active. 'Shut the door please' is not an active sentence, it is an imperative sentence, it has no subject. You could write something like this - You are asked to shut the door - but this is a bit awkward.
I think Knock on the door makes more sense. Knock at the door.... What do you knock on at the door? the wall?
No, knock is a noun (a knock on the door) and a verb (to knock on the door).
It can actually be used as both.Noun - For example: "I heard a knock at my door"Verb - To knock. For example: "I knocked on the door"
let the door be shut
The door was opened by whom.
This sentence is a command, it has no subject and it cannot be changed to a passive sentence.
The door was being knocked at by some body.
This
To change a sentence into passive the sentence must be active. 'Shut the door please' is not an active sentence, it is an imperative sentence, it has no subject. You could write something like this - You are asked to shut the door - but this is a bit awkward.
I think Knock on the door makes more sense. Knock at the door.... What do you knock on at the door? the wall?
No, knock is a noun (a knock on the door) and a verb (to knock on the door).
here i am i stand at the door and knock if any one here my voice and opens the door i will come eat with them and thy with me
it depends what knock on the door?
Rev 3:20 Listen! I stand at the door and knock; if any hear my voice and open the door, I will come into their house and eat with them, and they will eat with me.
I started to knock on the door. I will knock before I open the door.