One day, Tim's mathematic 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?"

　　Usually Tim's father did help him with his homework, but the evening before this, he had not been able to, because he had not been at home, so Tim answered, "No, sir. He was busy last night, so I had to do it all myself."

　　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？”

　　蒂姆的爸爸通常确实帮他做作业，但是头天晚上，因为他不在家就没能帮蒂姆，所以蒂姆回答说：“不，先生，我爸爸昨天晚上很忙，我不得不由我自己做了。”