Unit 9
      The major deserts in the world
9.1 What are deserts? Where do we find them?
9.2 What is desertification? What is a sandstorm?
9.3 How is China affected by desertification?
9.4 How do sandstorms affect us?
9.5 What can be done to solve the problem of desertification in China?
9.6 What can we learn form the experience of other countries/regions in the world?