【考研类试卷】考研英语648及答案解析.doc
《【考研类试卷】考研英语648及答案解析.doc》由会员分享,可在线阅读,更多相关《【考研类试卷】考研英语648及答案解析.doc(18页珍藏版)》请在麦多课文档分享上搜索。
1、考研英语 648及答案解析(总分:36.00,做题时间:180 分钟)一、Section Use of (总题数:1,分数:1.00)The human nose is an underrated tool. Humans are often thought to be insensitive smellers compared with animals, -|_|- this is largely because, -|_|- animals, we stand upright. This means that our noses are -|_|- to perceiving those
2、smells which float through the air, -|_|- the majority of smells which stick to surfaces. In fact, -|_|- , we are extremely sensitive to smells, -|_|- we do not generally realize it. Our noses are capable of -|_|- human smells even these are -|_|-to far below one part in one million. Strangely, some
3、 people find that they can smell one type of flower but not another, -|_|- others are sensitive to the smells of both flowers. This may be because some people do not have the genes necessary to generate -|_|- smell receptors in the nose. These receptors are the cells which sense smells and send -|_|
4、- to the brain. However, it has been found that even people insensitive to a certain smell -|_|- can suddenly become sensitive to it -|_|- to it often enough. The explanation for insensitivity to smell seems to be that the brain finds it -|_|- to keep all smell receptors working all the time but can
5、 -|_|- new receptors if necessary. This may -|_|- explain why we are not usually sensitive to our own smellswe simply do not need to be. We are not -|_|- of the usual smell of our own house, but we -|_|- new smells we visit someone else s. The brain finds it best to keep smell receptors -|_|- for un
6、familiar and emergency signals -|_|- the smell of smoke, which might indicate the danger of fire. The human nose is an underrated tool. Humans are often thought to be insensitive smellers compared with animals, -|_|- this is largely because, -|_|- animals, we stand upright. This means that our noses
7、 are -|_|- to perceiving those smells which float through the air, -|_|- the majority of smells which stick to surfaces. In fact, -|_|- , we are extremely sensitive to smells, -|_|- we do not generally realize it. Our noses are capable of -|_|- human smells even these are -|_|-to far below one part
8、in one million. Strangely, some people find that they can smell one type of flower but not another, -|_|- others are sensitive to the smells of both flowers. This may be because some people do not have the genes necessary to generate -|_|- smell receptors in the nose. These receptors are the cells w
9、hich sense smells and send -|_|- to the brain. However, it has been found that even people insensitive to a certain smell -|_|- can suddenly become sensitive to it -|_|- to it often enough. The explanation for insensitivity to smell seems to be that the brain finds it -|_|- to keep all smell recepto
10、rs working all the time but can -|_|- new receptors if necessary. This may -|_|- explain why we are not usually sensitive to our own smellswe simply do not need to be. We are not -|_|- of the usual smell of our own house, but we -|_|- new smells we visit someone else s. The brain finds it best to ke
11、ep smell receptors -|_|- for unfamiliar and emergency signals -|_|- the smell of smoke, which might indicate the danger of fire. (分数:1.00)A.althoughB.asC.butD.while二、Section Writing(总题数:1,分数:1.00)2. (1) effect of the countrys growing human population on its wildlife (2) possible reason for the effec
12、t (3) your suggestion for wildlife protection (1) effect of the countrys growing human population on its wildlife (2) possible reason for the effect (3) your suggestion for wildlife protection* (分数:1.00)_三、Section Reading(总题数:4,分数:4.00)Non-indigenous (non-native) species of plants and animals arrive
13、 by way of two general types of pathways. First, species having origins outside the United States may enter the country and become established either as free-living populations or under human cultivation-for example, in agriculture, horticulture, aquaculture, or as pets. Some cultivated species subs
14、equently escape or are released and also become established as free-living populations. Second, species of either U.S. or foreign origin and already within the United States may spread to new locales. Pathways of both types include intentional as well as unintentional species transfers. Rates of spe
15、cies movement driven by human transformations of natural environments as well as by human mobility-through commerce, tourism, and travel-greatly exceed natural rates by comparison. While geographic distributions of species naturally expand or contract over historical time intervals (tens to hundreds
16、 of years), species ranges rarely expand thousands of miles or across physical barriers such as oceans or mountains. Habitat modification can create conditions favorable to the establishment of non-indigenous species. Soil disturbed in construction and agriculture is open for colonization by non-ind
17、igenous weeds, which in turn may provide habitats for the non-indigenous insects that evolved with them. Human-generated changes in fire frequency, grazing intensity, as well as soil stability and nutrient levels similarly facilitate the spread and establishment of non-indigenous plants. When human
18、changes to natural environments span large geographical areas, they effectively create passages for species movement between previously isolated locales. The rapid spread of the Russian wheat aphid to fifteen states in just two years following its 1986 arrival has been attributed in part to the prev
19、alence of alternative host plants that are available when wheat is not. Many of these are non- indigenous grasses recommended for planting on the forty million or more acres enrolled in the U.S. Department of Agriculture Conservation Reserve Program. A number of factors perplex quantitative evaluati
20、on of the relative importance of various entry pathways. Time lags often occur between establishment of non-indigenous species and their detection, and tracing the pathway for a long-established species is difficult. Experts estimate that non-indigenous weeds are usually detected only after having b
21、een in the country for thirty years or having spread to at least ten thousand acres. In addition, federal port inspection, although a major source of information on non-indigenous species pathways, especially for agriculture pests, provides data only when such species enter via closely-examined rout
22、es. Finally, some comparisons between pathways defy quantitative analysis-for example, which is more “important“: the entry path of one very harmful species or one by which many but less harmful species enter the country? (分数:1.00)(1).Which of the following statements about species movement is best
23、supported by the text?(分数:0.20)A.Human factors affect its rates more than its long-term amount.B.Natural expansions of species account for their slow contractions.C.Natural environments created by humans facilitate species movement.D.Long-range species movement relies on the ranges of mans mobility.
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
下载文档到电脑,查找使用更方便
2000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 考研 试卷 英语 648 答案 解析 DOC
