新托福TPO 17综合写作训练详细解析：鸟类数量减少的原因

　　阅读材料：

　　In the past century, the steady growth of the human population and the corresponding increasing in agriculture and pesticide use have caused much harm to wildlife in the United States birds in particular. Unfortunately for birds, these trends are likely to continue, with the result that the number of birds in the United States will necessarily decline.

　　在过去的一个世界，人类数量的增加以及随之而来的农业生产的发展和杀虫剂的增加使得很多美国的野生动物受到了影响，而这种问题在鸟类上表现得更为明显。更加不幸的是，由于人口数量、农业生产和杀虫剂使用的趋势不会改变，美国的鸟类数量将会必然地随之下降。

　　First, as human populations and settlements continue to expand, birds natural habitats will continue to disappear. Forests, wetlands, and grasslands will give way to ever more homes, malls, and offices. As the traditional areas suitable for birds keep decreasing, so will the size of the birds populations that depend on those vanishing habitats.

　　首先，随着人口数量和居住面积的不断扩张，鸟类天然的栖息地持续地减少。森林、湿地和草原都变成的住宅、商场和写字楼。随着那些传统的适宜鸟类栖息的地方持续减少，失去赖以生存栖息地的鸟类，数量自然是减少的。

　　Second, agricultural activities must increase to keep pace with the growing human population. The growth of agriculture will also result in the further destruction of bird habitats as more and more wilderness areas are converted to agricultural use. As a result, bird populations in rural areas will continue to decline.

　　第二，为了能够满足增长的人口数量，农业活动也必须随之增加。农业的增加的代价是进一步破坏鸟类的栖息地，越来越多的荒地变成了农业用地。因而，鸟类在乡村的数量也随之持续减少。

　　Third, as human settlements expand and agriculture increases, the use of chemical pesticides will also increase. Pesticides are poisons designed to kill agricultural and home garden pests, such as insects, but inevitable, pesticides get into the water and into the food chain for birds where they can harm birds. Birds that eat the poisoned insects or drink contaminated water can die as a result, and even if pesticides do not kill birds outright, they can prevent them from reproducing successfully. So, pesticides have significantly contributed to declines in bird population, and because there will continue to be a need to control agricultural pests in the future, this decline will continue.

　　第三，随着人类居住地的扩展和农业的发展，化学农药的使用也增加了。农药是用来杀死诸如昆虫之类的生长在农田或者菜园的害虫的有毒物质。不可避免的是，这些农药会进入水系和食物链，进而伤害鸟类。鸟类会吃被毒死的昆虫或者喝污染了的水。这样会导致鸟类的死亡，即便不会不会导致鸟类的立刻死亡，也会影响鸟类的繁殖。所以，杀虫剂会对鸟类的数量有非常严重的影响。同时，因为即便是在将来，还是需要杀虫剂来控制农业害虫，所以，鸟类数量减少的趋势难以改变。

　　阅读部分需要提取的观点是：

　　- Main point: 三个原因导致鸟类数量减少

　　- Sub point 1: 人类居住地的增加

　　- Sub point 2: 农业用地的增加

　　- Sub point 3: 杀虫剂的使用

　　听力材料：

　　The passage claims that there will be fewer and fewer birds, but the arguments used to support this claim are unconvincing.

　　阅读文章声称鸟类的数量会越来越小，但是所使用的理由都是没有说服力的。

　　First, its true that urban growth has been bad for some types of birds, but urban development actually provides better and larger habitats for other types. So much so, that city and suburban dwellers often complain about increased bird populations seagulls at landfills, pigeons on the streets and so on. Even birds like hawks and falcons can now be found in cities, where they prey on the increasing populations of pigeons and rodents. So, its not going to be a story of uniform decline of bird populations in the future. Some populations may shrink, but others will grow.

　　首先，确实城市的发展对于一些鸟类是不利的，但是城市的发展事实上也为其他的鸟类提供了更大更好的栖息地。这样发展，城市的居民常常抱怨鸟类数量过多：堆填区的海鸥，大街上的鸽子，等等等等。甚至那些不常出现在城市里的鸟类，比如鹰类也出现在城市，这是因为他们可以捕捉数量不断增加的鸽子和啮齿类动物。所以，将来不会是所有鸟类的数量都在减少。有一些的数量在减少，但是其他的在增加。

　　As for agriculture, its true that it too will increase in the future, but not in the way assumed by the reading passage. The truth is, in the United States, less and less land is being used for agriculture every year. Increases in agricultural production have resulted from and will continue to result from the introduction of new, more productive varieties of crops. These new crops produce more food per unit of land, and as a result, theres no need to destroy wilderness areas.

　　对于农业来说，确实需求会越来越大，但是农业的增长并不是以阅读所提及的方式实现的。在美国，实际上用在农业领域的土地每年都在减少。农产品产量的增加是因为引进了新的、产量更高的农作物品种，而这种趋势将会持续。这些新的农作物有更高的亩产量，因而，就没有必要破坏原有荒地用作农耕了。

　　And third, while its certainly true that traditional pesticides have been destructive to birds, its incorrect to project this history into the future. Now that, people are aware of the possible consequences of traditional pesticides, two changes have occurred. First, new and much less toxic pesticides have been developed, and thats important. Second, and perhaps more importantly, there is a growing trend to develop more pest resistant crops, crops that are genetically designed to be unattractive to pests. Pest resistant crops greatly reduce the need for chemical pesticides, and best of all, pest resistant crops dont harm birds at all.

　　第三，尽管传统的杀虫剂的确会给鸟类带来损害，但是用过去推测未来的想法是站不住脚的。现在人们已经意识到了传统杀虫剂可能带来的危害，因而采取了两个措施。首先，已经研究出了新型的、毒性更小的杀虫剂，这是很重要的一个改变。而第二点可能是更为重要的，就是现在正在研究能够抵抗虫害的作物。通过设计，使得农作物在基因上具有不吸引害虫的能力。抗虫害作物能够极大的减少对化学杀虫剂的需求。更为重要的是，抗虫害作物对鸟类是完全无害的。

　　听力部分需要提取的观点是：

　　- Main point: 阅读部分的主张是站不住脚的

　　- Sub point 1: 人类的居住地的扩张不会导致所有鸟类数量的下降，有的会增加

　　- Sub point 2: 因为新品种作物的种植，农业用地会越来越少

　　- Sub point 3: 新型杀虫剂的毒性变小，并且正在研制新型抗虫害作物，将来杀虫剂不会继续伤害鸟类