“Je devais avoir trois ou quatre ans”

Question

When to use devoir in the imparfait or the passé composé is very difficult (at least for me). The related lesson in this exercise advises that the imparfait for devoir is used for “supposed to”, and the passé composé is used for “had to” or “must have”. So using that logic, the sentence : “I must have been 3 or 4” should have been translated as “J’ai dû avoir trois ou quatre ans”, but that seems to be incorrect.

Maybe more clarification is needed on that lesson with more examples, because this answer seems to be a contradiction to the lesson .

Accepted Answer

Hi Paul,
I understand your frustration as the use of the imperfect tense is very difficult for English speakers. I haven't done this particular exercise and cannot find the link to the lesson on devoir you mention but can answer why we use the imperfect in -
'....I must have been three or four '...
It describes a state of being which indicates duration in French and can only be conveyed by using the imparfait .
'Cette année-là , je devais avoir trois ou quatre ans' is correct .
The following examples will,I hope, illustrate how  'devoir' will be in the perfect or imperfect tense depending on what you are trying to say -
Hier, j'ai dû quitter le bureau à 15 heures pour aller à l'hôpital = Yesterday I had to leave the office at 3 pm to go the hospital
This happened and the action is finished.
Compare with the following -
Hier, Je devais quitter le bureau à 15 heures mais je n'ai pas pu = Yesterday, I was supposed to leave the office at 3 pm but I wasn't able to
If you let me have the link to the aforementioned lesson I will see if something needs to be altered .
Merci d'avance.

Answer

The lesson is titled : When to use « Devoir » in L’imparfait or Le Passé Composé.Thanks