一、dear sir/madam:

　　i"m delighted you have accepted our
invitation to speak at the conference
in [city] on [date].

　　as we agreed, youll be speaking on
the topic "" from [time] to [time]. there
will be an additional minutes for questions.
would you please tell me what kind of
audio-visual equipment youll need. if you
could let me know your specific requirements
by [date], ill have plenty of time to make
sure that the hotel provides you with what
you need.

　　thank you again for agreeing to speak.
i look forward to hearing from you.

　　sincerely yours,

　　[name]

　　[title]

　　二、dear sir/madam:

thank you for your letter of [date].

　　im glad that you are also going to [place]
next month. it would be a great pleasure
to meet you at the [exhibition/trade fair].
our company is having a reception at
[hotel] on the evening of [date] and i would
be very pleased if you could attend.
i look forward to hearing from you
soon.

　　yours sincerely,

　　[name]

　　[title]

　　三、dear sir/madam:

　　[organization] would very much like
to have someone from your company speak
at our conference on [topic].

　　as you may be aware, the mission of
our association is to promote . many of
our members are interested in the

　　achievements your company has made in .
enclosed is our preliminary schedule for
the conference which will be reviewed in
weeks. ill call you [date] to see who from
your company would be willing to speak to
us. i can assure you that well make everything convenient to the speaker.

　　sincerely yours,

　　[name]

　　[title]

　　首先是主人（邀请人）的姓名（要用全称）或头衔；第二部分是“requests the pleasure (或者honor)of",相当于汉语的“恭请”第三部分是客人（被邀请人）的姓名（要用全称）（加’s）或用your (泛指）；第四部分是“presence at ..." 相当于汉语中的“光临。。。”第五是日期；第六是钟点第七是地点给你的例子： mr. xxxx requests the pleasure of "s presence at party on friday, the18th of january at7o". at huaxing hotel xxxx road答案补充
dear mr brown, we take pleasure in inviting you to present the annual gathering of import and export corporation in tianjin. on november20th XX, in huaxia hotel. we are looking forward that you can make a report on potential for economic development in tianjin. please fax the date of your arrival, enableing us to make the necessary preparations. yours faithfully,limingpublic relations manager