Esercizio di grammatica inglese on-line per studenti del livello elementare sul verbo modale 'must'. Completa la frasi con il verbo modale must.
1) They _______________ in the class. (not smoke)
2) I ______________ my room before I go out. (tidy)
3) You _____________ some medicine for that cough. (take)
4) Susan, you _____________ in the street! (not play)
5) We _______________ our homework. (do)