In 20 13, China suffered the worst smog weather in history. Read the national map of foggy days 20 13 12 1 ~ 6 and answer 1 ~ 9 according to your own knowledge.

Pipeline is a modern transportation mode suitable for transporting liquids and gases. Its advantages are large transport capacity, low freight rate, low loss, safety, reliability, strong continuity and convenient management, and it is not affected by meteorological disasters (such as smog and cold wave). However, there are also shortcomings such as large equipment investment and poor flexibility. With the increase of oil and natural gas production, China's pipeline transportation has developed rapidly.

So choose: C.