Breakdown of Das Telefon wurde von einem Lehrer erfunden.
ein
a, an (eine)
der Lehrer
the teacher
von
from, of / by (agent in passive clauses)
werden
to be (passive auxiliary + past participle)
Questions & Answers about Das Telefon wurde von einem Lehrer erfunden.
How is the past passive formed in this sentence?
This sentence uses the simple past (Präteritum) of the passive voice. To form it, you take the past tense of werden, which is wurde, and place the past participle of the main verb (erfunden) at the very end of the sentence.
Why do we use von to mean 'by' here?
In German passive sentences, the person or institution performing the action (the agent) is introduced with the preposition von. If the action were caused by an object, a process, or a force of nature, you would typically use durch instead.
Why does it say von einem Lehrer instead of von ein Lehrer?
The preposition von always forces the following noun phrase into the dative case. Because Lehrer is a masculine noun, the article ein changes to its dative form, einem.
What is the infinitive of erfunden and why doesn't it start with ge-?
The infinitive is erfinden (to invent). Because it starts with the inseparable prefix er-, it does not take the usual ge- prefix when forming the past participle. Other common inseparable prefixes include be-, emp-, ent-, and ver-.