Il doit être ici. Must be, probably is.
Je dois partir demain. I am to leave to-morrow.
Je devais partir hier. I was to leave yesterday.
Il devra revenir. Will have to...
Ils ont dû vendre leur maison. Have had to...
Elle aurait dû le faire. Ought to have done...
Ils devraient étudier. Ought to study...
Il aura dû s'arrêter. Must have had to...
Etc.

1. The king must be a ridiculous man. 2. Lucas was a homely man
but his little gift must have pleased[1] Fanny. 3. She looked[2]
happy, seated by the fireside. 4. Poor Fanny was to carry the
beautiful pears to market. 5. I had gotten that far[3] when John
arrived. 6. They have let it[4] be understood[5] that they are
going to move. 7. I was supposed to fill a hard rôle. 8. The
old king must have gotten impatient.[6] 9. You ought to have
told me in the first place what[7] was the cause of the delay.
10. They were in the act[8] of raising the curtain, when the
king arrived. 11. You will have to hold your tongue, otherwise[9]
we will not get along together very well. 12. One[10] ought not
to forget one's[11] benefactors. 13. If Jean wanted to get the
place, he ought not to have forgotten the pears. 14. Where is
Jean? He must be at the steward's. 15. Where have we gotten to?
[12] 16. The steward was a worthy[13] man. 17. The new servant
must have forgotten her good intentions. 18. The king wanted
them[14] to raise the curtain. 19. I am afraid he will leave.[15]
20. I am afraid he cannot[16] get the place.