3句英文任你选
 
I'm sorry I can't keep our appointment because something unexpected has come up.
对不起，我们的约会我不能去了，因为出了一点意外的事。

I'm sorry to inform you that I have to cancel the lunch date with you.
很抱歉告诉你，我不得不取消和你的午餐约会。

It looks as if I won't be able to keep the appointment we made.
看来我不能赴约了。

半个句型要记牢

keep one's appointment(遵守约定)

Tip: keep是最常用的动词之一，其含义丰富，与其搭配的短语也很多，作及物动词时可表示"保留，保持，赔养，经营，使……处于某种状态(情况) " 等，如 We'd better keep a seat for him. (我们最好给他留个座位)，在例句中是"履行，遵守"的意思，如keep one's promise. (信守承诺)。