Stepping on the first ray of sunshine in the morning, Stu-qing returned home.

Mama Zhang is preparing breakfast in the kitchen. When she sees him, she wonders, "Hey, Qing, why did you come back from outside and still wear the clothes you wore last night?"

"I went out to buy soybean milk and steamed buns late." Stuqing lifted the bag in his hand and showed it to Mama Zhang.

"When I came back to my room last night, I heard a door ring. I didn't see anybody. Did you go out at that time?" Zhang Ma knows that Stu usually goes out in the morning wearing morning exercise clothes.

"Yes,...