15. be glad/happy/sad to do sth.“很高兴/难过做某事 I am glad to see you. 16. reply to sb./sth.“回复…” Reply in writing to the invitation “以写信形式回复这份邀请函” 【重点语法】 一. 表示邀请的句型 1. Can/Could you…(come to my party)?