Two months ago, you and some former classmates decided to go for an outing to the Summer Palace during the National Day holidays. As the organizer, you are to write an email message to remind the others of:
　　（1）when and where to meet,
　　（2）what to bring, and
　　（3）why they have to tell you in advance whether they will come.
　　Do not sign your own name at the end of the letter. Use “Li Ming” instead. You do not need to write the address.