This sentence is already in the passive. The verb is "BE + -ed" and there is no actor (who opened it?).
The active version of this sentence is "Someone opened the parcel secretly."
you opened the door
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.
The door was opened by whom.
language you use when you are writing or talking. no it is passive
virus
before that Amy secretly pressed the real self-destruct button!
Let's see what happened when he opened that door... The dog opened the doggie door slowly, at first.
If she had opened up her feelings to someone, she would not have ended up this depressed.
Example sentence - We opened an oyster to see if it had a pearl in it.
I opened the envelope that contained my check.
I was the cicerone as i opened your mothers legs.
The new superstore was opened