Hi, I am still having trouble with this one. Any help would be so very much appreciated.

Hi Ian,

the rule, as explained in the corresponding lesson, is the following: put the verb "être" into the required tense, followed by the past participle of the verb (don't forget to match gender and number with the subject!). For example:

The apple is eaten. -- La pomme est mangée
The apple was eaten. -- La pomme était mangée (imparfait)
The apple has been eaten. -- La pomme a été mangée (passé composé)
The apple had been eaten. -- La pomme avait été mangée (plusqueparfait)
The apple will be eaten. -- La pomme sera mangée (future simple)
The apple will have been eaten. -- La pomme aura été mangée (future éxacte)

-- Chris (not a native speaker).

Bonsoir Ian, I have the same question that you posted. Slowly but surely, I am trying to learn these conversions in each tens/mood. I have found simply memorizing them and using them in the practice quizzes is the best way for me. Bonne chance et bonne continuation.

I don't understand why we can't use the 

Passé Composé

when there is no reference to a duration of time. For example "during that year the letters had been sent"??? This sentence seems like it was a one time action. ???