Dear Miss White,
I’m so sorry to tell you that I broke my leg on my way home this evening. I went to see the doctor and he said that I 'd better to stay home all day long tomorrow, so I cannot take part in your English training which I have looked forward to for a long time. But I think I will feel better the day after tomorrow. I am sure I will go to the speech contest on that day.
Best regards!
Yours,
Li Ming