Reply in writing to the invitation “以写信形式回复这份邀请函”
be glad/happy/sad to do sth.“很高兴/难过做某事I am glad to see you.
Can/Could you.(come to my party)?
Would you like to..( Would you like to my party)?接受:Sure/Yes/Of course, I’d love/like to.
I’m sorry, I can’t. I have to/must+V 原 (陈述理由 )
I’d love/like to, but I . (理由) I’m afraid not. I.(理由)