Passive with modal verbs

Modal verbs do not have a passive voice types, however, they can be combined with a passive infinitive of a full verb. The differentiation between personal and impersonal passive applies also to modal verbs.

Example for the personal passive:

active				passive
	modal verb		+ active infinitive		modal verb	+ passive infinitive
Der Mechaniker	muss	den Motor	reparieren.	Der Motor	muss	repariert werden.

The following changes take place:

	The subject of the active voice sentence is not mentioned in the passive voice sentence.*
	In the active voice, the modal verb governs the active infinitive; in the passive voice, it governs the passive infinitive.
	The accusative object of the active voice sentence becomes the subject of the passive voice sentence.

* The subject of the active voice sentence can be mentioned in the passive voice sentence by using a prepositional phrase introduced by the prepositions von or durch. The indefinite pronoun man is an exception; it cannot be mentioned as an agent in the passive voice sentence when it is the subject of the active voice sentence.