Occasionally, for a formal party or dinner, an invitation requires an answer, either in writing or by telephone, but even if a reply is not requested, it is still courteous, to let your host know whether you expect to attend.

• 应邀出席正式宴会或晚餐，不管是用书面还是用电话，有时是要回复的，不过即使不要回复，为了礼貌，也应该让主人知道你是否参加。