The size and location of the world's deserts are always changing. Over millions of years, as climates change and mountains rise, new dry and wet areas appear. But within the last hundred years deserts have been increasing after frightful speed. This is partly because of natural changes, but most responsible for creating deserts are men.     Man can make deserts, but they can also prevent them from getting bigger. Algeria is planning a green belt of trees along the edge of the Sahara Desert to stop the sand. In China, too,  _ are being built in the northwest to keep the desert from growing.     But desert still threaten the world. Experts believe that land that is on the way to becoming deserts equals the size of Australia, Russia and US put together. Can we stop the spread of the world's deserts and save the land that is so essential to mankind? Yes, we can, and we must. Which of the following do you think is the best method?
People move away from the land that is on the way to become deserts To build great walls to stop the wind and sand To plant trees and grass on the surface of the tree To irrigate the desert
Question: The size and location of the world's deserts are always changing. Over millions of years, as climates change and mountains rise, new dry and wet areas appear. But within the last hundred years deserts have been increasing after frightful speed. This is partly because of natural changes, but most responsible for creating deserts are men.     Man can make deserts, but they can also prevent them from getting bigger. Algeria is planning a green belt of trees along the edge of the Sahara Desert to stop the sand. In China, too,  _ are being built in the northwest to keep the desert from growing.     But desert still threaten the world. Experts believe that land that is on the way to becoming deserts equals the size of Australia, Russia and US put together. Can we stop the spread of the world's deserts and save the land that is so essential to mankind? Yes, we can, and we must. Which of the following do you think is the best method?
A. People move away from the land that is on the way to become deserts
B. To build great walls to stop the wind and sand
C. To plant trees and grass on the surface of the tree
D. To irrigate the desert
Answer: