1. They MUST be twins, they look identical.
2. That man CAN'T be Prince Charles, he's not tall enough.
3. They MUST be rich. They live in a huge castle.
4. He MAY be our new history teacher but I'm not sure.
5. It CAN'T be our flag. Not with those colours.
6. I think the currency of Slovakia is Korunas, but I MAY be wrong
1.must
2.can't
3.must
4.may
5.can't
6.may