钱丽英编的
Mr Black has two cats. One is big and other is small. He likes them very much. One day his feiend Mr Green comes to see him. He is very surprised. He finds there are two holes in the door, a big hole and a small one. He says,"My dear feiend, why are there two holes in your door?""To let them in and out," Mr Black answers. "But why are there two holes?" asks his feiend. " How can the big cat go through the small hole?" he says.