<正> In a school,the class has just begun.The teacher asked a student:“Mart-in,can you tell us how people know the age of hens?”“According to the teeth,sir.”“But hens don’t have any teeth.”“Perhaps hens don’s have any.But I have.If its flesh is tender,the henis young;if the flesh is hard,the hen is old.”(上海高永伟选辑)