假设你是李明，你的一个朋友张伟准备到你所在的城市来旅游，但你有事不能接待。写封信给他，解释你不能接待的原因，并说明你所做的安排。
Dear Zhang Wei,
I'm glad to knoing to my city during the summer vacation.
However, I'm afraid there's some bad news. I'm planning to take part in an international conference to be held in another city during the time of your visit. All the top scientists in my field will show up at the conference. More importantly, I'm lucky enough to have been selected to give a speech on behalf of my research team at the Conference. I really can't miss it.
I understand that it'll be your first time to this city and I'm your only friend here. I've asked my roommate to meet you at the airport, and you can stay in my room. He is a very nice person and he will show you around the city. Hope you two will get on well and have a nice holiday!
Yours,
Li Ming