4. A. Never mind.                       B. Not a bit.                        C. Of course.

3. A. On the third floor.                     B. It's very big.                    C. He is working in it.

2. A. She is sleeping.                  B. She is a teacher.               C. She is well.

1. A. It's James.                         B. It's Billy's.                       C. It's on the desk.