self-addressed envelope

[-əˈdrest-]
noun ,

self-addressed stamped envelope

(US) [-əˌdrestˈstæmpt-]
noun

busta affrancata e indirizzata per la risposta

Complétez la séquence avec la proposition qui convient.

This exercise … be difficult, my younger brother can do it!
- mustn't
- can't
- must