Answer:
She may be overworked.
He must have very small salary.
That must be very tiring.
That man can't be her grandfather.
He might be rich.
They can't start another argument.
We may already know each other.
She may have had an unhappy childhood.
She might think I'm upset.
Explanation:
The sentences presented in the question above were rewritten in a summarized form, using the required verbs. All sentences kept the main meaning of the original sentences and were written according to spelling and grammatical standards, maintaining the verbal and nominal agreement between all the words presented, leaving them coherent and cohesive.