1. Your roommate overslept and missed an important meeting at work.
He / She could . . .
He / She might . . .
2. Your best friend hasn't called you in a week.
He / She may . . .
He / She couldn't . . .
3. Your grandparents forgot your birthday.
They may not . . .
They might . . .
4. Your sister can't find her favorite earrings.
She must . . .
She could . . .