根据所给中英文信息完成应用文。

     Lucy 在暑假去了中国旅游。Tom 对Lucy 假期去中国的经历很感兴趣，给Lucy 写了一封电子邮件。假设你是Lucy ，请根据Tom 的邮件内容写一封回信。要求至少五句话。

Dear Tom,

     I heard that you went to China which holds the 29th Olympic Games during the summer vocation. I

feel so happy for you. And I also want to visit China, so I have many things to ask you. How did you

travel there, and how did you feel when you arrive there? Were the people there friendly to you? What

different things from your country America did you see?I hope that I can travel to China as soon as

possible. And I'm looking forward toyour e-mail.

Dear Tom,

     So glad to hear from you                                                                                                                    

双代号网络图中，某非关键工作的拖延时间不超过自由时差，则（）。

A.后续工作最早可能开始时间不变

B.仅改变后续工作最早可能开始时间

C.后续工作最迟必须开始时间改变

D.紧后工作最早可能开始时间改变