大家都来给我帮忙啊，今晚收到尼日利亚客户的邮件，他们要来中国参观我们的工厂，我把邮件的内容贴出来，希望大家给我指点一下，我该怎么做，我是新手。Dear Amy.Ok, i will send the passport to you by tomorow and we 4people that's comming, two of my staff and 2 of my customer that want to buy from you direct and kindly note that we are comming with 30% cash to pay in your office for the deposit of our order.Pls, could you tell us how many days the invitations Letter will stay b/c we can get it to enable us arrange everything at once both our ticket.Pls, confirm to me as soon as possible.TnksUwkaonye还有就是，开邀请函的程序是什么？到哪里开？需要多长时间？其中我应该注意什么？有专门介绍如何开邀请函的网站吗？我先谢谢大家了。