You and some of your classmates decide 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; 3) why they have to tell you in advance whether they will come. You should write about 100 words. Do not sign your own name at the end of the letter. Use 'Wang Ling' instead.