Prepositions in passive constructions – von, durch and mit


In order to indicate by whom or what an action is done, the preposition von has to be used:
Er wurde von einem Polizisten verhaftet. He was arrested by a policeman.

Two other prepositions often used in passive structures are durch, which expresses by what means the action is carried out and mit, which identifies what implement is being used:
Das Haus wurde durch einen Brand zerstört. The house was destroyed by fire.
Er wurde mit einem Messer getötet. He was killed with a knife.

Note that the preposition durch requires the accusative; von and mit are followed by the dative case.

Using the correct case

When transforming a sentence into a passive construction, the direct object (accusative) of the active sentence usually becomes the subject in the passive version:

Der Vater holt den Sohn (direct object) ab. The father collects the son.
Der Sohn (subject) wird vom Vater abgeholt. →  The son is collected by the father.

As the subject of the passive sentence has to be in the nominative case, the appropriate nominative form has to be used.

Verbs taking the dative

A verb taking the dative needs a different structure in the passive. The dative object moves to the beginning of the passive sentence and is followed by the relevant form of werden. Here are a few examples:

Der Frau wird von den Kindern geholfen. The woman is being helped by the children.
Mir wurde geraten, mehr Sport zu treiben. I was advised to do more sport.
Ihm wurde eine Taschenuhr geschenkt. He was given a watch.
Ihnen wurde zu ihrem Lottogewin gratuliert. They were congratulated on their lottery win.

Omitting the ‘doer’

Note that passive constructions do not always reveal who or what initiated the action. This omission occurs in order to focus more on the action itself rather than on the ‘doer’:

Das Meeting wurde abgesagt. The meeting was cancelled.
Werden Sie schon bedient? Are you being served?