I always wanted to change a new schoolbag, but my parents said that the schoolbag I used now was pretty new. So I told them that if I did well in the exam, they should buy me a new one. They were happy to say yes. I studied very hard for my goal. At last, I made great progress and my parents answered my wish. 
我一直想换一个新的书包，但是我父母说我现在用的书包还很新。因此我跟他们说如果我考得好，他们应该给我买一个新的。他们很高兴地答应了。我为我的目标努力学习，最后，我取得了很大的进步，我的父母实现了我的愿望。