She isn't answering the door. She can't be at home.

(It’s impossible for her to be at home because she isn't answering the door.)
Look at all those football trophies. She must be a really good player.

(It’s very likely that she is a good player because of all the trophies.)
He has a strong Chinese accent. He must be from China.

(It’s very likely that he is from China because of his accent.)
You've just had lunch. You can't be hungry.

(It’s impossible that you’re hungry right after eating lunch.)
They haven't had a drink all afternoon. They must be thirsty.

(It’s very likely that they are thirsty after not drinking all afternoon.)
He lives in a big house. He must be rich.

(It’s very likely that he is rich because he lives in a big house.)
Nobody is buying her cakes. They can't taste very nice.

(It’s impossible for the cakes to taste good if nobody is buying them.)
She's got a lot of books. She must love reading.

(It’s very likely that she loves reading because she has a lot of books.)