The verb devoir usually means must / to have to (see Conjugate devoir in Le Présent (present tense)).
However, in past context, its meaning changes depending on whether you use Passé composé or Imparfait.
Devoir in Imparfait = I was supposed to [do]
Il devait me rappeler, mais il a oublié !
He was supposed to call me back, but he forgot!
Ils devaient venir ce soir, mais ils ont annulé à la dernière minute.
They were supposed to come tonight, but they cancelled at the last minute.
Nous devions nous rejoindre à 17h. Qu'est-ce qui s'est passé ?
We were supposed to meet at 5pm. What happened ?
Maintenant que ses parents n'étaient plus là, elle devait s'occuper de sa sœur.
Now that her parents were gone, she had to take care of her sister.
Actually, in most cases, the obligation was not met.
To conjugate devoir in Imparfait, see Conjugate regular verbs in L'Imparfait (imperfect tense)
Devoir in Passé composé = I had to [do] / I must have [done]
Il est parti tôt, donc j'ai dû faire la lessive moi-même.
He left early, so I had to do the laundry myself.
Nous étions en retard, donc nous avons dû appeler un taxi.
We were late, so we had to call a taxi.
Il a dû le laisser là pour toi.
He must have left it there for you.
J'ai trouvé l'écharpe de Sophie. Elle a dû l'oublier.
I found Sophie's scarf. She must have forgotten it.
- a past obligation that was met.
or
- the likeliness of an action having taken place, a hypothesis on a past situation.
To conjugate devoir in Passé composé, see Conjugate voir, devoir, pouvoir, boire, croire, savoir, lire, taire (+ avoir) in Le Passé Composé (conversational past)
Learn more about these related French grammar topics
Examples and resources
Il devait me rappeler, mais il a oublié !
He was supposed to call me back, but he forgot!
J'ai trouvé l'écharpe de Sophie. Elle a dû l'oublier.
I found Sophie's scarf. She must have forgotten it.
Ils devaient venir ce soir, mais ils ont annulé à la dernière minute.
They were supposed to come tonight, but they cancelled at the last minute.
Maintenant que ses parents n'étaient plus là, elle devait s'occuper de sa sœur.
Now that her parents were gone, she had to take care of her sister.
Il est parti tôt, donc j'ai dû faire la lessive moi-même.
He left early, so I had to do the laundry myself.
Nous devions nous rejoindre à 17h. Qu'est-ce qui s'est passé ?
We were supposed to meet at 5pm. What happened ?
Il a dû le laisser là pour toi.
He must have left it there for you.
Nous étions en retard, donc nous avons dû appeler un taxi.
We were late, so we had to call a taxi.
Ann
Kwiziq community member
28 January 2019
2 replies
The way I understand devoir, it can mean inevitability in the imparfait such as Il eva it perdre un jour. in the test question, the answer for she had
to replace him was "Elle a dû" vs if it was inevitable, shouldn't "Elle devait" be correct as well?
Chris
Kwiziq community member
29 January 2019
29/01/19
Elle a dû le remplacer. -- She had to replace him.Elle devait le remplacer. -- She was supposed to replace him.
Ann
Kwiziq community member
29 January 2019
29/01/19
From the thought co: You can also use devoir to express fatalism or the fact that something is inevitable:
Il devait perdre un jour. > He had to / was bound to lose one day. Elle ne devait pas l'entendre avant lundi. > She wasn't to hear it until Monday.