四、书面表达。
假如你是 Jack,你的朋友 Henry 发来电子邮件询问你上周过得怎么样。请你根据以下提示和要求,给他回复一封电子邮件,告诉他你经历的尴尬事。
提示：上周日你去超市买背包,当你挑好背包准备付钱时,发现钱包落在家里了,你只好回家去取。在回家的路上,你遇到了你的朋友 Tom,你向他借了些钱。但是当你再次返回超市买那款背包时,却被告知已经售完了。
要求：
1. 根据以上提示信息进行写作,可适当发挥；
2. 适当运用本单元重点语法 —— 过去完成时；
3. 100 词左右(电子邮件的格式和开头已给出,不计入总词数)。
Dear Henry,
I had a very embarrassing experience last Sunday.
Yours,
Jack

Dear Henry, I had a very embarrassing experience last Sunday. I went to buy a backpack in the supermarket. There were many kinds of backpacks and finally I chose one. When I was going to pay for it, I found I had left my wallet at home. I had to go back home to fetch it. Luckily, I met my friend Tom on my way home. I borrowed some money from him. But when I went back to the supermarket, I was told that kind of backpack had already been sold out. What a pity! Yours, Jack