You must study harder if you want to pass the exam.

She must follow the rules if she wants to join the club.

They must arrive on time for the meeting tomorrow.

I can't believe they forgot my birthday again!

He can't be serious about quitting his job without another one lined up.

We can't go to the concert tonight because we have other plans.

You mustn't talk during the movie or you'll disturb other viewers.

She mustn't forget to buy milk on her way home from work.

They mustn't leave the house unlocked when they go on vacation.