One day, Tim's mathematics teacher looked at his homework and saw that he had got all his sums right. The teacher was very pleased-and rather surprised. He called Tim to his desk and said to him, You got all your homework right this time, Tim. What happened? Did your father help you? 

　　No, sir. He was too busy last night, so I had to do it all myself, said Tim. 

　　你爸爸帮你了吗？ 

　　一天，蒂姆的数学老师看了他的作业，发现他全做对了。老师很高兴，同时也十分惊讶。他把蒂姆叫到桌前说：蒂姆，你这次的作业全都做对了，怎么回事？你爸爸帮你做了吗？ 不，先生，我爸爸昨天很忙，我不得不全由自己做了。