Grammaire 1: les expressions de nécéssité
On étudie !
(1) Le verbe devoir
Qu’est-ce que tu dois faire? (What do you have to do?/What must you do?)
There are many ways to express necessity and obligation in French. The verb devoir is a useful way to express necessity and obligation.
Conjugaison du verbe devoir (to have to, must)
| Singulier | Pluriel |
|---|---|
| je dois | nous devons |
| tu dois | vous devez |
| il, elle, on doit | ils, elles doivent |
Pronunciation hints: the letters oi are pronounced <wa> and the 3rd person plural like <dwav>.
Some examples with devoir:
| Je dois finir mes devoirs avant la classe. | (I must finish my homework before class.) |
| Henri doit ranger sa chambre parce qu’elle est sale. | (Henri has to tidy his room because it’s dirty.) |
| Nous ne devons pas faire la vaisselle dans la baignoire! | (We must not do the dishes in the bathtub!) |
(2) Il faut
The impersonal expression il faut (it is necessary…) is also a very common way to express necessity. In this expression, the subject pronoun il (it) does not refer to a specific person or thing. The obligation applies to people in general or the context may indicate the particular people concerned.
| Pour apprendre le français, il faut pratiquer. | (To learn French, it is necessary to practice.) |
| Il faut arroser cette plante deux fois par semaine. | (It is necessary to water this plant twice a week.) |
(3) DEVOIR/IL FAUT + infinitive
Whether you use the verb devoir or the set group of words ‘il faut’, these 2 expressions of necessity are always followed by an infinitive.
This is a construction we have seen with other verbs such as:
- aimer, to express likes and dislikes: j’aime danser (I like to danse)
- savoir and pouvoir, to express abilities: je sais parler français, je peux pratiquer en classe (I know how to speak French, I can practice in class)
- vouloir, to express desires: il est fatigué, il veut dormir (he is tired, he wants to sleep)
- aller, to express future actions: Nous allons voyager à Montréal l’été prochain (we are going to travel to Montréal next summer)
a) If you are wanting to negate and state what you must not do, place ne…pas around the verb:
Vous ne devez pas dormir au travail (il ne faut pas faire ça!)
(You must not sleep at work (you must not do that!))
b) Other ways to express necessity and obligation include:
être obligé de… (to be obligated to…), il est necessaire de.. (it is necessary to…).
Sam habite seul et il est obligé de payer un gros loyer. (Sam lives alone and he has to pay a big rent.) Il est nécessaire de visiter beaucoup d’appartements avant d’en choisir un. (It is necessary to visits a lot of apartments before choosing one.)
