Dear Bill, I'm glad to receive your letter,thank you for your caring for the weather and my health.But I am sorry to tell you that I have to stay at home because of the heavy fog and haze . Since the winter last year,the fog and haze has appeared a lot of times.it has done great harm to our daily life.Many traffic accidents happened just because of the heavy fog and haze weather,more and more people have to go to see the doctor because the serious disease caused by the fog and haze ,quite a lot of flights have to be put off,a great number of people have to stay at home for fear of the poisonous air caused by the fog and haze. According to the Chinese Academy of Science,driving car and burning coal are two main reasons.People have been told : Don't do outdoor sports;If you have to go out,wear a _ ; wash your face and clean your nose as soon as you get home. People have realized the great harm caused by the fog and haze and the importance of protecting the environment.People all over the country are taking measures to reduce the fog and haze weather.The government suggests people go to work or school with the public traffic, such as the bus and the underground.Also we should plant more trees. According to me, I will go to school by bike or on foot, and I won't throw the waste anywhere.In addition, I will tell the people I meet to protect the environment as possible as they can.Would you like to tell me some good ideas?I'm looking forward to your reply. Yours, Li Hua Li Hua didn't go to school because  _  .
he was ill there was heavy rain there was heavy fog and haze because it was Sunday