вставьте пропущенные слова don t /doesn t или mustn t.
we make noise . my little sister is asleep.
i spend mush money .
i do this exercise in writing.
he forget to mail this letter tomorrow.

We mustn't make noise. My little sister is asleep.  I mustn't spend much money . I mustn't do this exercise in writing.  He mustn't forget to mail this letter tomorrow.