Modal auxiliaries exercises

Modal auxiliaries exercises. Choose the right answers in the following sentences.

There's someone at the door. It ______ the postman.
1. must be
2. can be
Don't worry, you ______ pay now.
1. don't have to
2. mustn't
I think you ______ take an umbrella with you. It's going to rain heavily.
1. had better
2. would better
Wilson _____ the CEO if Brown has to resign.
1. could be
2. must be
Sorry, I can't stay any longer. I _____ .
1. have to go
2. might go
It was 3 o'clock two hours ago. Your watch ______ right.
1. can't be
2. mustn't be
It's a dress code, all the employees _____ a uniform.
1. have to wear
2. must wear
I suppose that our team ______, but I'm not absolutely sure.
1. should win
2. must win
Let's tell her about it. She _____know.
1. might not
2. could not
In my opinion, the management _____ something about this.
1. should do
2. might do