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Since last winter, the smog has occurred a lot of times in China. It has done great harm to our daily life. Many traffic accidents happened just   the heavy smog weather. Many coaches and planes had to be  . In Nanjing, all primary and middle schools and kindergarten classes    as heavy smog hit the city. People have realized  protecting the environment. People all over the country are taking measures to reduce the smog weather. The government suggests people go to work or school  , such as the bus and the underground. Also we should plant more trees.