Martin is an American boy. He’s eight years old. One evening, jimmy, one of his classmates, came to his home with an exercise book in his hand. “Could you help me 1 this math problem?” Jimmy said as soon as he came into the room. “It’s too hard for me to work it out.”“Let me 2 ,” Martin said. “I hope it isn’t hard for me.”Martin tried his best but he couldn’t work it out, either. “If we had a small computer, all the probems would be easy enough for us to do,” Jimmy said.“A small computer...” Martin thought for a minute, then he said, “I’ve got a(n) 3 . We can buy one in a shop!” “A computer is very 4 , and we don't have enough money.” “That’s OK,” said Martin. “we can ask the new president(总统)for some money. He said hewould help anyone in trouble. I 5 he will help us. He is very 6 , you know.” So they decided to write a letter to the new president. Soon they finished the letter and hurried to the 7 .In front of the post office stood a small box. They 8 the letter into the box carefully and went home 9 .The next morning, they passed the post office on their way to school. They found, to their surprise, the box was not a post-box 10 a trash can(垃圾箱)