1Forests help to keep water from running away, so drought does not often happen. The trees in the forests can keep raindrops from hitting the soil directly, and the dead leaves on the ground can also keep the water from running away.2 Chinese people don't want to see more floods and droughts. We have built the " Great Green Wall" of trees across the northern part of our country.3 Thanks to the " Great Green Wall", we can prevent the wind from blowing the earth away. It will stop the sand from moving towards the rich farmland. That's why more " Great Green Walls" are needed. Trees must be planted all over the world.4 ,A, B, C, D,. (10) We have built the " Great Green Wall" of trees  _  of China.
in the east in the west in the south in the north.