One evening in early summer, because of the investigation of a case, the sheriff visited Mary, an art teacher. She lives on the top floor of the luxury apartment. "Yesterday around three o'clock in the afternoon, where were you?" Investigation

One evening in early summer, because of the investigation of a case, the sheriff visited Mary, an art teacher. She lives on the top floor of the luxury apartment.

"Yesterday around three o'clock in the afternoon, where were you?" The detective asked her to present proof of absence.

"Sketching on the platform, this is the painting." Mary showed him an oil painting on an easel. The painting is a view of the skyscraper from the top of the building, and the painting is very good. "I was hospitalized for three months due to a traffic accident, and I was just discharged from the hospital the day before yesterday, so I have been painting since yesterday, and I am good at relieving my boredom, and it is a good sunbathing day in a row!" "No wonder the face is black and red, it looks quite healthy, I think it is also sunburned." What time is it? Unfortunately I forgot to wear my watch. The sheriff asked nonchalantly. Half past six. Mary replied by looking at the watch she was wearing on her left wrist. Her left finger was as white and delicate as a white fish, and it was beautiful.

She sensed the sheriff's keen gaze paying attention to her hand, "What's wrong with my hand?" She asked uneasily. I can't help but be mesmerized by your beautiful fingers. You're right-handed, right? "Well, yes, so what?" "I find it strange that you sunbatheed and painted for two days, but your left hand was not tanned at all." "My left hand is holding a paint plate, so I didn't have a sunbath!" Mary was halfway through her words, when she suddenly felt that she had lost her mouth and hurriedly closed her mouth.

Clever little friend, why do you think Mary should shut up?