假设你是李华，最近参加了为期两周的“伦敦夏令营”活动。期间你住在Smith夫妇家中，他们为你提供了吃、住、行及旅游方面的帮助。请写一封电子邮件感谢他们。内容需要包括以下要点：
1.已安全回到中国家中；
2.感谢Smith夫妇的帮助。
注意：
1.词数100左右；
2.开头已写好，不计入总词数。
Dear Mr. and Mrs. Smith,
How time flies!
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
Yours,
Li Hua