1991年考研数一真题答案

1987-2019年 历年考研数学真题解析 视频+PDF文档 无偿分享考研数学真题讲解：每日一练206天一、题目2013年线性代数真题二、解析题目1解析题目2解析考研路上，你我同行。加油！泰笛牛考研数学

2019年考研的成绩已经出来了，下面让我们一起回顾一下数一真题

声明即日起，博林考研正式并入文都教育，加入文都考研大家庭！燕郊文都考研来到你身边啦！优秀的人总是互相吸引，博林考研全心全意为学生服务，不断提高服务质量。期待以全新的身份服务每一位新同学。文都考研，大家早已耳熟能详。但小编有必要隆重介绍一下：文都集团在考研、四六级、教资、中小学、留学、医考、建考、公考等领域多元化发展。文都考研积累了丰富的教学管理经验，并建立了优秀的管理团队。以数学汤家凤老师、英语何凯文老师、谭剑波老师、政治蒋中挺、万磊老师，为核心的教师团队，深受全国各地学生喜爱。并出版了大量优质考研用书。（比如今年考研数学多数证明题是汤老师的《接力题典1800》书中原题）回归到今天的主题，给大家分享下考研真题及答案解析。回忆版真题，仅供参考，如有错误欢迎各位考生留言：2020数学一真题答案解析

考研数学真题讲解：每日一练192天一、题目2011年考研数学真题二、解析考查：方程的根考查：含抽象函数记号的多元函数求偏导考研路上，你我同行。加油！

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The fact is that the energy crisis, which has suddenly been officially announced, has been with us for a long time now, and will be with us for an even longer time. 事实是，虽然官方突然宣布能源危机的存在，然而长期以来我们一直面临着能源危机，而且这种情况今后将会持续更长的时间。Whether Arab oil flows freely or not, it is clear to everyone that world instry cannot be allowed to depend on so fragile a base.不管阿拉伯的石油能否源源不断地流出，人人都清楚，再也不能让世界工业依赖于如此脆弱的能源基础了。The supply of oil can be shut off unexpectedly at any time, and in anycase, the oil wells will all run dry in thirty years or so at the present rate of use.石油供应可能随时会被突然切断；不管怎样，以目前这种消费速度，只需30年左右，所有的油井都会枯竭。New sources of energy must be found, and this will take time, but it is not likely to result in any situation that will ever restore that sense of cheap and plentiful energy we have had in the times past.必须找到新的能源，这需要时间；而过去我们感觉到的那种能源廉价而充足的情况将不大可能再出现了。For an indefinite period from here on, mankind is going to advance cautiously, and consider itself lucky that it can advance at all.在今后的漫长的时间内，人类将谨慎前进，而且应该对自己能够继续前进感到非常幸运。To make the situation worse, there is as yet no sign that any slowing of the world’s population is in sight. Although the birth-rate has dropped in some nations, including the United States, the population of the world seems sure to pass six billion and perhaps even seven billion as the twenty-first century opens.使目前状况更糟的是，至今尚无迹象表明，世界人口的增长在近期内会减慢。虽然包括美国在内的一些国家的出生率已经下降，但是在21世纪初世界人口似乎肯定会超过60亿，或许甚至超过70亿。The food supply will not increase nearly enough to match this, which means that we are heading into a crisis in the matter of procing and marketing food.食品供应的增加将远远赶不上人口的增长，这就意味着我们在粮食的生产和购销方面已陷入危机。Taking all this into account, what might we reasonably estimate supermarkets to be like in the year 2001?考虑到所有这些因素，我们可以适当地估计一下2001年的超级市场将会是什么样子呢？To begin with, the world food supply is going to become steadily tighter over the next thirty years -- even here in the United States. By 2001, the population of the United States will be at least two hundred fifty million and possibly two hundred seventy million, and the nation will find it difficult to expand food proction to fill the additional mouths.首先，今后的30年内，世界的食品供应日益紧张，甚至美国这里也不例外。到2001年美国人口将至少达到2亿5千万，也可能是2亿7千万。那时，美国将很难扩大食品生产来满足人口增长的需要。This willbe particularly true since energy pinch will make it difficult to continue agriculture in thehigh-energy American fashion that makes it possible to combine few farmers with high yields.这种困境将是确定无疑的，因为能源的匮乏使农业无法以高能消费这种美国耕作方式继续下去了，而按照这种耕作方式可以投入少数农民就获得高产。It seems almost certain that by 2001 the United States will no longer be a great food-exporting nation and that, if necessity forces exports, it will be at the price of belt-tightening at home.几乎可以肯定，到2001年美国将不再是一个食品输出国；如果必须出口的话，那么其代价就是美国国内人民将勒紧裤带。In fact, as food items will tend to decline in quality and decrease in variety, there is very likely to be increasing use of flavouring additives.实际上，由于各种食品往往会质量下降、品种减少，这就非常有可能更多地使用调味添加物。Until such time as mankind hasthe sense to lower its population to the point where the planet can provide a comfortable supportfor all, people will have to accept more “unnatural food”.除非人类终于意识到要把人口减少到这样的程度，使地球能为所有人提供足够的饮食，否则人们将不得不接受更多的“人造食品”。

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本文说明了水对于生长的植物的重要作用。第一段：Most growing plants contain much more water than all other materials combined.大部分生长的植物，其水的含量超过其他所有物质的含量总和。C. R. Barnes has suggested that it is as proper to term the plant a water structure as to call a house composed mainly of brick a brick building.C·R·巴恩斯认为，把植物叫做水结构就如同把主要用砖盖成的房子叫做砖建筑一样恰当。Certain it is that all essential processes of plant growth and development occur in water.当然，植物生长的一切必要过程都发生于水中。The mineral elements from the soil that are usable by the plant must be dissolved in the soil solution before they can be taken into the root.来自于土壤的矿物质在被植物根茎吸收之前，必须先溶解于水。They are carried to all parts of the growing plant and are built into essential plant materials while in a dissolved state.它们在溶解状态被输送到植物的全身并构成基本的植物材料。The carbon dioxide (CO2) from the air may enter the leaf as a gas but is dissolved in water in the leaf before it is combined with a part of the water to form simple sugars -- the base material from which the plant body is mainly built.空气中的二氧化碳能以气体的形式进入叶子，但在和一部分水结合生成单糖（构成植物体最基本的材料）之前也必须先溶于水。Actively growing plant parts are generally 75 to 90 percent water.植物生长活跃部分的含水量一般高达75-90%。Structural parts of plants, such as woody stems no longer actively growing, may have much less water than growing tissues.植物的结构部分（如生长不活跃的木质茎）的含水量可能大大少于生长活跃的组织。第二段：The actual amount of water in the plant at any one time, however, is only a very small part of what passes through it ring its development.但是，植物任何时候的实际含水量都只是其生长期间通过它全身水量的很小一部分。The processes of photosynthesis, by which carbon dioxide and water are combined -- in the presence of chlorophyll (叶绿素) and with energy derived from light -- to form sugars, require that carbon dioxide from the air enter the plant.借助叶绿素和光能量发生光合作用（二氧化碳和水结合）以形成单糖的过程要求二氧化碳从空气中进入植物。This occurs mainly in the leaves. The leaf surface is not solid but contains great numbers of minute openings, through which the carbon dioxide enters.这一过程主要发生在叶子上。叶子表面并非固体，而是有大量的小口。二氧化碳通过这些小口进入植物。The same structure that permits the one gas to enter the leaf, however, permits another gas -- water vapor -- to be lost from it.这些允许二氧化碳进入叶子的小口却让另一种气体——水蒸气散失。Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10,000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80℉, saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake.由于二氧化碳在空气中的含量非常少（3-4‰），且叶子内部空气空间的水蒸气含量接近饱和状态（80F时，饱和状态下的每10000份空气中含186份水汽），所以，植物失去的水蒸气的量是吸收的二氧化碳量的许多倍。Actually, because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater than the relative concentrations of the two gases.实际上，因为风和其他因素的影响，损失掉的水和吸入二氧化碳的比甚至可能大于这两种气体的相对浓度。Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates (碳水化合物).另外，并非所有进入叶子的二氧化碳都可以被合成碳水化合物。19. A growing plant needs water for all of the following except .[A] forming sugars[B] sustaining woody stems[C] keeping green[D] procing carbon dioxide[分析] 本题考核知识点：事实细节题。第一段第六句（the carbon dioxide…mainly built）和第二段第二句说明：二氧化碳可以直接从空气中进入植物的叶子里，所以不需要水。[D]选项正确。同时这两句还说明：生成糖的过程需要二氧化碳先溶于水，然后和水结合，所以[A]不是正确选项。第一段最后一句说明：（尽管木质茎比活跃组织需要的水少得多），但还是需要一定量的水。所以，[B]非正确选项。[C]文中未提及。20. The essential function of photosynthesis in terms of plant needs is .[A] to form sugars[B] to derive energy from light[C] to preserve water[D] to combine carbon dioxide with water[分析]本题考核知识点：文中细节推理题。第一段第五句说明：二氧化的作用主要是生成植物体最需要的材料——单糖。第二段第二句说明：植物的光合作用（二氧化碳和水结合）形成单糖。所以，光合作用能够提供植物需要的（单）糖。[A]为正确选项。[B]的干扰来自于第二段第二句，但该句提到的是从光中获取能量是光合作用的条件之一，而不是反过来通过光合作用去获取能量。[C]文中未提及。[D]是光合作用的过程，而不是作用。21. The second paragraph uses facts to develop the essential idea that.[A] a plant efficiently utilizes most of the water it absorbs[B] carbon dioxide is the essential substance needed for plant development[C] a plant needs more water than is found in its composition[D] the stronger the wind, the more the water vapor loss[分析] 本题考核知识点：段落主旨题。解此题需要分析第二段的结构。本段第一句为段落主题句：植物的含水量只是其需水量很小的一部分。然后用事实说明为什么会出现这种情况（植物叶子允许二氧化碳进入，却让水蒸气散失。再加上风和其他因素的作用，大部分的水都损失掉了）。所以，[C]为正确选项。[A]“有效利用水”不是本文涉及的内容；[B]只在第一段有所提及。第二段提到风等因素造成水的损失，但并未提到风的大小与损失的水蒸汽的量相关。所以，[D]排除。22. According to the passage, which of the following statements is TRUE?[A] The mineral elements will not be absorbed by the plant unless they are dissolved in its root.[B] The woody stems contain more water than the leaves.[C] Air existing around the leaf is found to be saturated.[D] Only part of the carbon dioxide in the plants is synthesized.[分析] 本题考核知识点：文中多处细节理解题。文章第二段最后一句指出：并非所有进入叶子的二氧化碳都被合成了碳水化合物。这说明[D]选项正确。[A]的干扰来自于第一段第四句。该句说明，来自于土壤中的矿物质元素只有先溶于“土壤溶液”才能被“根部”吸收，而非溶解于“根部”。[B]与原文内容相反：从第一段最后一句可知，生长不活跃的木质茎含水量可能远远小于生长活跃的叶子。[C]与文中内容不符：第二段第五句给出的信息是：“叶子内部”空气中的水蒸气含量“接近”饱和状态，而非“叶子周围”的空气“处于”饱和状态。23. This passage is mainly about.[A] the functions of carbon dioxide and water[B] the role of water in a growing plant[C] the process of simple sugar formation[D] the synthesis of water with carbon dioxide[分析] 本题考核知识点：文章主旨题。本文第一段首先通过类比开门见山地说明水对于生长中植物的重要作用。然后通过水对植物生长的各种功能（溶解矿物质元素、溶解二氧化碳并和二氧化碳结合生成单糖）说明植物生长中的一切重要过程都离不开水。第二段用事实说明：（尽管植物含水量相当高），但植物生长所需要的水远远大于其本身所所含有的水。所以，整篇文章说围绕的中心是：水对于植物生长的重要作用。[B]为正确选项。考生误选[A]、[C]、[D]都是因为对光合作用在全文中作用的理解错误：文中提到关于二氧化碳（光合作用）是为了用事实说明水对植物生长的重要作用，而并非为了说明二氧化碳本身或光合作用（生成单糖）的作用，所以[A]、[C]都不正确；同样也不是为了说明光合作用的过程，所以[D]错误。