This joke is too short.

One day, a university teacher asked a student that there were ten birds in the tree, one was shot dead, how many were left?

The student asked: Is it silent pistol? No, how loud was the shot? 80- 100 decibel. Is it illegal to shoot birds in this city? No offense. Are you sure that bird was really killed? Of course. At this time, the teacher was impatient: "Will you just tell me how many birds are left?" Are there some deaf birds in the tree? No. Have you ever been caged and hung from a tree? No. Are there any other trees nearby? Are there any other birds in the tree? No, if a bird is pregnant, is it a bird in its belly? Not exactly. Is there a flower in the bird photographer's eye? There are no flowers, only ten. The teacher was sweating all over, and the bell rang, but the students continued to ask: Are there any stupid birds that are not afraid of death? Fear of death. Would you kill two with one shot? No, the student said confidently, if your answer is not a lie, "if the bird that was killed hangs on the tree and doesn't fall, there is only one left." If it falls, there will be none left. " . The teacher immediately foaming at the mouth fell to the ground!