You must (be/have/do something)

Use this expression when you want to make a guess about someone. It's really useful when you're trying to be nice to someone and predict what they want. For example, you might say this to someone who's a guest at your house:

You must be starving!

This phrase also shows that you understand a person's feelings:

You must feel quite a sense of accomplishment.

This phrase appears in these lessons: