Throughout human history, autumn must be one of the words mentioned most. Someone may think that god spills paints every autumn which forms a colourful and marvelous world. The bule sky and fresh air give us the best opportunity for hiking. In their mind, autumn is the best season of the year. On the other hand, many people easily feel sad during this season. A chilly morning always prevents them from going outside and exercising. The indoor temperature is also very low. In fact, these feelings is our response to cold weather. We'd better go out and enjoy the limited sunshine. The weather in autumn often gives us some illusion that we are in winter in the morning and in summer at noon. As for some areas, people have been enjoying the heaters which keep the room temperature at a comfortable degree. In that case, we also need to do some outdoor activities which can help us keep our lungs healthy in the cold air. A variety of flu germs and virus have been on the way. We need to keep fit to fight against them soon. Are you ready?