Is war unavoidable? Can war be prevented? History tells that there were wars, great or small, in every century, in every decade. Throughout the ages, from the Stone age to the Atomic Age, men have been fighting, first with swords and shields , then with guns and cannons, and now, hydrogen bombs and missiles are used for military purpose. But, in spite of all these, it is still my belief that war can be prevented and peace can be won, but it requires the effort of every one of us. I am sure that we would not like to experience another world war. If it ever happens, two-thirds of the world and much of the civilization which men have gained through time, patience and effort will be destroyed. Will then the remaining one-third of the world be able to survive on its own? Our task now is not to blame the past, but to plan for the future. If there is peace in the world, men can use their rockets to explore the mystery of space, their submarines to explore the depth of the sea, their missiles to deliver mails and their fine equipment to penetrate  the jungles of Africa, instead of using them military. Governments can use their money to build more schools, so that more children can be educated to be useful citizens. Scientists can use atomic energy to propel   steamships and planes. They can also design new machines to increase the production of goods and thus improve the way of living of the people. How can a peaceful world be achieved? It requires, in my opinion, the understanding and friendship between all people from all nations. Let no one suffer discrimination by reason of color, race, religion, or national origin. Let the rich support the poor and the strong help the weak. We know that neither peace nor such a dream world can come true in a day or a month. It may even take decades or centuries. But let us plan and begin now. We can infer from the passage that   _  .
wars were not expensive in the past wars can promote the development of weapons things for military use can be transformed to peaceful use as long as there are wars, people's way of living cannot be improved