Present Tense:
* Ils doivent: This is the most common translation for "they must" in the present tense.
* Il faut qu'ils...: This is used when you want to express a general obligation or necessity. For example, "Il faut qu'ils aillent à l'école." (They must go to school.)
Past Tense:
* Ils durent: This translates to "they had to" or "they were obliged to."
* Ils devaient: This translates to "they should have" or "they were supposed to."
Future Tense:
* Ils devront: This translates to "they will have to" or "they will be obliged to."
Examples:
* They must go to the store. - Ils doivent aller au magasin.
* They must finish their work. - Il faut qu'ils finissent leur travail.
* They had to leave early. - Ils durent partir tôt.
* They should have studied more. - Ils devaient étudier davantage.
* They will have to work late tonight. - Ils devront travailler tard ce soir.
Remember to choose the correct tense and phrase based on the specific context of your sentence.