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    In l620, about half the USA was covered by forests. Today the forests have almost gone. A lot of good land has gone with them, leaving only sand. China doesn't want to copy the USA's example. We're planting more and more trees. We've built the "Great Green Wall" of trees across northern part of our country. The Great Green Wallis 7, 000 kilometres long, and between 400 and 1, 700 kilometres wide. It will stop the wind from blowing the earth away. It will stop the sand from moving towards the rich farmland in the south.

     However, more "Great Green Walls" are needed. Trees must be grown all over the world. We wish to have more Green Walls and the world becomes a better place for people to live in.

1. （1） In 1620, about          the USA was covered by forests.

   A . a third B . half C . two thirds D . a fourth
3. （2） A lot of good land has gone with      .

   A . sand B . water C . wind D . forests
5. （3） The Great Green Wall in China is       long.

   A . 7, 000 kilometers B . 1,700 kilometers C . 7, 000 meters D . 400 kilometers
7. （4） Trees must be grown in       .

   A . China B . the USA C . some countries D . every part of the world
9. （5）        will make the world better.

   A .   The Great Wall B .   Tall buildings C .   Great Green Walls D .   Flowers and grass