全新版大学英语视听阅读4视频听力原文翻译

Unit 1The Perfect SwarmNarrator:Damage from swarms of locusts can reach disastrous proportions. A single swarmof desert locusts can consume over 70,000 metric tons of vegetation a day. There is, however,one continent that’s locust-free: North America.旁白：蝗虫群的伤害可以达到灾难性的程度。一个单一的沙漠蝗虫可以消耗超过 70000 吨的植被一天。然而，有一个大陆是蝗虫自由：美国北部。Interestingly enough, this wasn’t always true. For hundreds of years, the Rocky Mountain locustwas a common pest in the American West. Back in the mid-1800s, thousands of pioneersjourneyed across the U.S. in search of free land and new opportunities. They settled on thefrontier of the western states, and began to farm the land intensively, growing corn and othercrops.有趣的是，这并不总是真实的。几百年来，落基山脉的蝗虫是美国西部的一种常见害虫。早在 19 世纪中叶，成千上万的先驱者跨越美国在自由的土地和寻找新的机会。他们定居在西部边境，并开始对土地进行集中耕种，种植玉米和其他农作物。Then, in 1875, out of nowhere, a rare combination of air currents, drought, and basic biologyproduced the right conditions for an unthinkable event, the worst storm ever recorded, the“perfect swarm.” It came over the horizon like a strange, dark cloud. Not millions, not billions, buttrillions of insects, sweeping through the land like a living tornado. Those who saw the incredibleevent and survived never forgot what they witnessed.然后，在 1875，走出无处，一个罕见的组合，空气电流，干旱，和基本生物学产生了正确的条件为一个不可想象的事件，最坏的风暴有史以来，“完美的群”，它在地平线上像一个奇怪的，黑暗的云。不是上百万，不是数十亿，而是数以万亿计的昆虫，像一个活生生的龙卷风席卷过大地。那些看到了令人难以置信的事件，并幸存下来的人从来没有忘记他们见证了什么。The swarm came together over the state of Texas, and soon moved quickly across the front...