"Good morning!" The masked man smiled politely as he walked into the room.

"I thought it would be a doctor!" I blurted out. Seeing this man on such a bright morning made me forget how to use polite language. My heart has a certain expectation, but also a kind of embarrassment.

"I am a doctor!" The man put a first-aid box on the table in the room. He opened the box and took out a stethoscope and a medical flashlight.

"Come and lie down on the bed," he said.

I went over and lay down on the bed. He expertly placed one end of the stethoscope on my chest. The...