We mainly collect the information about your everyday traveling such as going to work or school and other traveling within past 7 days. Simple demographic data such as gender and age will also be collected. There are not any sensitive or private questions in the questionnaire, so you will not feel any discomforts. Meanwhile we will not begin the face to face survey until obtain oral informed consent from you. We promise that all the information you provide will be kept secret strictly. You will be voluntary for the survey. If you are not willing to take part in our survey, it would not bring any bad impact for you. It will take you less than 10 minutes to finish the survey, we feel sorry for bothering you. If you have any question, please consult our investigators, we will try our best to explain for you.