After world war ii, with the recovery and prosperity of the world economy and the rapid growth of the population, the world appeared to be internationally popular tourism. The progress of science and technology has greatly improved the traffic conditions. Create conditions for travel; The improvement of labor productivity, people disposable income increase, to travel and enjoy the hotel's service record for expanded rapidly, speed up the popularization and the world of tourism activities in political, economic and cultural exchanges and frequent. This change in social needs pushed the restaurant industry into the modern hotel period. Work hard. In spring and summer, some people increase their intensity. According to experts, proper exercise can help you lose weight and exercise, but excessive exercise can be harmful. Especially in the summer, due to the movement of large amount of sweat, if excessive movement, not only the body moisture loss fast, potassium and other important elements also can rapid loss, serious lack of potassium will lead to coma and even death. In addition, some work has been quite heavy intensity of white-collar workers need to consider before fitness problems, don't in the case of very tired or according to the intensity of exercise at ordinary times, in order to avoid instead of fitness is a health hazard, and even cause irreparable consequences. According to a newly released research "The National Heath Interview Survey" conductedby the Centers for Disease Control and Prevention, home health aides, law enforcement officers, physicians arethe shortest sleepers in US. Base onanalyzingindividual sleep habits and job requirements, the survey shows thatnone of them sleep 8 - hours which we had arrived all taught to bethe leastfor our healthy life. 3. The confidence Some harmful substances combine with water vapor and become more toxic, such as sulfuric acid or subsulphide, hydrolysis of chlorine to hydrogen chloride or hypochloric acid, and fluoride hydrolysis to hydrogen fluoride. As a result, air pollution in haze days is much more serious than usual. In addition, it is also easy to induce cardiovascular disease.