[解析]
Dear Bill,
I'm glad to receive your letter. I have learned from your letter that you are concerned about the smog which frequently appears in some areas of China.【高分句型一】 Thank you for your concern.(感谢他的关注) I'm also worried about such terrible weather because it has brought much inconvenience or rather harm to people's health. Besides, as a result of the terrible air quality, a large number of students have to stay at home during workdays. The efficiency makes both teachers and parents worried a lot, since some students just stayed at home doing nothing but playing computer games or watching videos for the whole day.(简介雾霾带来的危害,以及停课期间你们的学习情况)
From my point of view, schools as well as students ourselves should do something to make full use of the time.【高分句型二】 Since we are living in an information era, schools and teachers can broadcast lessons or provide videos through the Internet. For us students, we should make a timetable everyday and keep ourselves away from computer games, online chatting and so on. Only thus can we make full use of the time at home.(谈谈对于雾霾停课期间学校和学生应如何合理安排时间的看法)
Yours,
Li Hua