I don't understand the structure used in this exercise:

What's it called?
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There are two types of passive: "true passive" and "statal passive" (or "Zustandspassiv"). Compare these "true passive" sentences (of which one is analagous to the OP's):
to these "statal passive" sentences:
According to the Handbuch zur Deutschen Grammatik, the difference between the two is a
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It is Perfekt Passiv of bauen ... Vorgangspassiv to be precise.
I will not give translations as the notion of the tenses in German and English are not the same. Both past forms are to an extend interchangeable. What threw you of was probably the missing ge. This is special for the verb werden. Its participle 2 (the ge-form) is geworden but as soon as it is combined with another participle 2 (gebaut) the ge disappears. Double ge would sound strange. We already know, that we are in Perfect Tense and once is enough. |
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That's passive voice in perfect tense:
Passive in past tense would be
As to why this passive structure uses "worden" instead of "geworden", here's an explanation I found in a forum post:
(links and emphasis mine) |
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There are different problems with that sentence, i think. Besides the verb, there's a noun ellipsis, because the noun „im Jahr“ / „in the year“ is missing. Maybe it's easier to recognize with the noun at its place:
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