a short summer vacation I'm a college student in Changsha,while my hometown is Yunnan,thousans miles away form there.Summer vacation and Winter vacation is the only chance which I can go back home.However,I'm going to play a role in China Undergraduate Mathematical Contest in Modeling,and my college arranged many courses for CUMCM,from August 1st to 21st.So that my summer vacation is only 15 days.My parents is not very happy for it because I can just stay with them for a while.I miss them so much and want to stay with them longer,but I just can't.