英语请假条下午要做试验,不能上外教的口语课,但是不会写请假条,请高手帮下忙,请假条请要充分表达我不能上课的抱歉和遗憾,请

Dear professor
I am so sorry that I can not be in your class this afternoon,because I have a lab to do this afternoon.I apologize that.
Sincerely,
your name.

诶？楼上两位心心相惜诺 呵呵

Dear professor:
I'm vey sorry that I can't be in your class this afternoon, because I have a lab to do this afternoon. I apologize that.
Sincerely,
(your name)