Percakapan bahasa inggris tentang must do and must not do

1. You must do your homework
2. You must not play with sharp object

Must
Mrs. Mona: Hey Clarice! Come Here!
Clarice: What's wrong mrs. ?
Mrs. Mona: You must study harder to get a good score. Your parents must be dissapointed of you.
Clarice: Mmm ... Okay miss, i promise i'll study harder. So i can make my parents proud of me and not dissapointed anymore.

Mustnt't/Must Not
Mrs. Mona: It's about you again, Clarice ...
Clarice: Mrs. Mona, i begging you to give apologize of me. I promise, someday i'll make my parents proud.
Mrs. Mona: Of course you have to, you mustn't often playing video game and your gadget for spending your weekday. Why don't you review your lesson, or study for the next topic? It must be good for your attitude and your score.