students welcomed by the director

Question

The student were welcomed by the principal

Les étudiants ont été accueillis par le directeur

Les étudiants étaient accueillis par le directeur.

The latter translation is correct yet the C1 Test marked it worng?

Accepted Answer

Bonjour Finn,
As Chris mentioned, this particular sentence is part of a lesson looking at La voix passive. Therefore, "ont été accueillis" is the expected answer. 
Sometimes you are right that Le Plus-que-Parfait can apply to sentences such as the one above. However, here it can't work: the time phrase "ce matin" (= this morning) brings the action too close to the present timeframe and therefore you cannot have Le Plus-que-Parfait.  
If the time phrase had been, "ce matin-là"(= that morning), then Le Plus-que-Parfait would have been correct.
I hope this is helpful. 
Bonne journée !

Answer

Salut Finn"Les étudiants ont été accueillis par le directeur"This is the correct sentence construction in the passive voice.Bonne continuationJim

Answer

The sentence asks for passé composé, which, in passive voice, requires ont été accueillis.
Étaient accueillis would be imperfect tense.