Read the joke.
Why must I go to school?
Early one morning, a mother went to wake up her son. "Wake up, son. It's time to go to school!"
"But why, Mom? I don't want to go."
"Give me two reasons why you don’t want to go."
"Well, the kids hate me for one, and the teachers hate me, too!"
"Oh, that's no reason not to go to school. Come on now, get up."
"Give me two reasons why I should go to school."
"Well, for one, you're 52 years old. And for another, you're the principal（校长）!"