change this sentence to passive ( Ihave adog)
However, this is idiomatic:
A good day was had by all.
To hell with grammar.
What do you mean by middle verbs?
I guess then, 'I have a dog.' put into passive would be:
A dog is had by me.
Whether this is ungrammatical or not doesn't matter; it sounds ridiculous!
1. Certain verbs describing states, such as have, be, belong, lack, resemble and seem, cannot be made passive. They cannot be used in the passive even when they describe an action.
The Passive Voice English Through Jokes