假定你是李华，与留学生朋友Bob约好一起去书店，因故不能赴约。请给他写封邮件，内容包括：
1.表示歉意
2.说明原因
3.另约时间
注意
1.词数100左右
2.可以适当增加细节，以使行文连贯。
因故不能赴约的致歉信英语作文范文：
Dear Bob,
I'm sorry to say that I cannot go to the bookstore with you on Friday afternoon. I have just found that I have to attend an important class meeting that afternoon. I hope the change will not cause you too much trouble.
Shall we go on Saturday morning? z.xxkWe can set out early so that we'll have more time to read and select books. If it's convenient for you, let's meet at 8:30 outside the school gate. z.xxk If not, let me know what time suits you best. I should be available any time after school next week.
Yours,
Li Hua