My home in Shiquan,where a beautiful rich,these are my hometown return with sweat.Indicated above are pictures that show trees play a vital role in water and soil conservation.In the left hand picture,people are fleeing from voracious sand dunes because they cut down all the trees.The caption reads,"As the sand advances,we retreat." In the right hand picture,the people have returned carrying tools,water and samplings for the reforestation of the land.We are informed that,"As we advances,the sand retreats."It seems that the cartoonist is sending a message about the significance of trees in water and soil conservation and the need for everyone to fight against the danger of the desertification.In fact,what he is saying is if we do not fight against the sand,it will drive us away from the land.If we let this situation go as it is,our environment will suffer a great destruction.改一下即可