Henry is nine years old. It is half a kilometer from his home to school, so he goes to school on foot every day. He usually gets home at five in the afternoon.

    It was Thursday, and he came home one hour late. When he came home, his mother asked him, “Why are you late, Henry?”

    “My math teacher Mr. Smith is very angry (生气的）with me and asks you to go to his office tomorrow.”

    “Why does Mr. Smith ask me to go to his office?” his mother asked. “He asked us a question and no one could answer it, but I could.”

    “What a clever boy! Then what was his question?” his mother asked with a big smile.

    “His question was ‘Who put some ice-cream on my chair and made my trousers dirty? "said Henry.