A joke, the professor asked the students some questions.

The next day, the biology teacher brought a bird wrapped in cloth. Then he exposed the bird's legs and asked the students to guess what kind of bird it was. I really don't know, so I handed in a blank sheet of paper. The teacher looked very angry and asked, "Why did you hand in a blank sheet of paper?" What's your name? "When I heard this, I rolled up my trouser legs angrily and said," Now it's your turn to guess who I am? "Biology teacher immediately fell ~ ~ ~ ~