I want to tell you about a kind of air pollution. I went to an industrial city last month, and I found that the air pollution there is quite serious. Inhabitant there told me that such a phenomenon has lasted for nearly two years. The main source of the pollution comes from two medicine plants. The plants discharge waste gas, which contains a lot of SO2. The smell is extremely smelly and the gas destroys people's health. The inhabitants there are always woken up by the bad smell,and they have serious headaches. Such a problem should be solved as quickly as possible. For example,the two plants should improve their technology, thus the pollution can be reduced. Moreover, the plants should be moved to a place with fewer inhabitants? Only in this way,people can thoroughly enjoy fresh air.It is quite important in our environmental protection timetable.