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《考研英语阅读理解100篇 高分版》 Unit 20 - TEXT ONE

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2019年02月19日

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Most cells are transparent—in other words, they are not very good at reflecting or absorbing light. To look at them under a microscope thus requires trickery. Many of these tricks kill the cells, and even those that keep them alive look only at slices through each cell, rather than seeing the whole thing in three dimensions.
Michael Feld, of the Massachusetts Institute of Technology, and his colleagues, think they can change that. They have invented a way to look at cells that are still alive. Moreover, they can do so in three dimensions. Their method is called tomographic phase microscopy, and it is reported in this week's Nature Methods. Instead of relying on absorbed or reflected light, Dr. Feld's technique celebrates transparency by looking at light that gets through unaltered. It does so by measuring a property called the refractive index.
This index measures the speed of light in a material. (Light zips along at the actual “speed of light”, faster than which nothing can go, only when it is travelling through a vacuum.) The different components of a cell, though transparent, have different refractive indices. Dr. Feld and his team therefore set out to map what these differences are, with a view to using them to distinguish between cellular components.
To measure the refractive indices of different parts of a cell they use a technique called interferometry, which involves splitting a beam of light in two. One half, known as the object beam, passes through the cell; the other is directed along a different path and acts as a reference. The length of the reference path is such that if no sample is present, the two daughter beams will be as perfectly in phase when they meet as they were when they were separated. The crests and the troughs of their waves will reinforce each other, and the result will be brightness. The more that the light passing through the sample is slowed down, however, the more the two beams will be out of phase. Crest will fall on trough, and the result will be darkness. It is this phase shift that gives Dr. Feld's new form of microscopy its name.
A single pair of beams does not, however, produce a useful image. To do that requires scanning the object beam through the target about a hundred different ways. From the refractive index of each path it is possible—with the application of some suitably crunchy computing power—to produce a three-dimensional image.
To test his idea, Dr. Feld looked at cervical-cancer cells. If you identify this cancer early, the patient will probably survive. Miss it, and she will die. Dr. Feld wondered if the changes that occur during cancer would show up using his new method. They did, in a part of the cell called the nucleolus. This is the place where the components of protein factories are made. Since cancer cells grow rapidly, and thus have a high demand for proteins, it was a likely place to expect changes.
Dr. Feld also has plans to use beams of different colours, since each colour has a slightly different refractive index in a given material. That would provide extra data for the computer to chew on, and probably result in better pictures. With enough pictures, Dr. Feld's technique may make biology as transparent as the cells it studies.
1. Tomographic phase microscopy is different from the other tricks that look at cells in that _____.
[A] the light that gets through the cells is unaltered in tomographic phase microscopy
[B] it does not require the trickery to kill cells
[C] it is not dependent on absorbed or reflected light
[D] it could see all the components of the cells from three dimensions
2. Which one of the following statements is TRUE of the speed of light in materials?
[A] Light runs the fastest when it passes through transparent materials in the real world.
[B] The speed of light can only be precisely measured when the light is traveling in vacuum.
[C] The speed of light in any material is slower than the actual “speed of light”.
[D] The speed of light shifts when the light travels through different cells.
3. The result of darkness in the technique of interferometry implies that _____.
[A] there is no light passing through the sample
[B] the refractive index of the sample is very great
[C] the speed of the light passing through the sample is very low
[D] the two daughter beams weaken each other
4. Dr. Feld's method could be applied into identifying cancer early by _____.
[A] detecting changes of refractive indices in the components of protein factories
[B] finding out the changes of the refractive indices in some parts of the cervical-cancer cells
[C] examining the changes of the refractive indices in the nucleolus
[D] identifying the changes of the refractive indices in part of the nucleolus of the cancer cells
5. The best title of the passage could be _____.
[A] Image of the Transparent Cells
[B] New Technique of Celebrating Transparency
[C] Refractive Indices of the Transparent Cells
[D] New Method of Detecting Cancer Cells

1. Tomographic phase microscopy is different from the other tricks that look at cells in that _____.
[A] the light that gets through the cells is unaltered in tomographic phase microscopy
[B] it does not require the trickery to kill cells
[C] it is not dependent on absorbed or reflected light
[D] it could see all the components of the cells from three dimensions
1. X线断层阶段显微法和其他观察细胞的方法的不同之处在于 _____。
[A] 穿过细胞的光在X线断层阶段显微法中是没有发生改变的
[B] 它不要求杀死细胞
[C] 它不依靠被吸收或反射的光
[D] 它可以从三个方位看到细胞的所有组成成分
答案:C 难度系数:☆☆☆
分析:细节题。选项A,第二段提到的是一些光穿过细胞时没有改变,但不代表所有的都没改变。选项B,根据第一段和第二段,该方法可以观察活细胞,但是之前的一些方法也可以观察活细胞,因此并不是二者的不同之处。选项C,第二段提到,该方法没有依靠被吸收或反射的光。选项D的内容文章中没有提到。因此,答案为C。
2. Which one of the following statements is TRUE of the speed of light in materials?
[A] Light runs the fastest when it passes through transparent materials in the real world.
[B] The speed of light can only be precisely measured when the light is traveling in vacuum.
[C] The speed of light in any material is slower than the actual “speed of light”.
[D] The speed of light shifts when the light travels through different cells.
2. 关于光在物质中的传播速度,下列哪个陈述是正确的?
[A] 光在穿过现实世界中的透明物体时的速度是最快的。
[B] 光速只有在真空状态下才能够被准确测量。
[C] 在任何物质中,光的速度都比“真正的光速”慢。
[D] 光穿过不同的细胞时,速度也会发生变化。
答案:C 难度系数:☆☆☆
分析:细节题。根据第三段,光在真空中速度最快,而真实世界中也存在真空,因此选项A是错误的。选项B的错误则在于,虽然其表述正确,但是却与题干要求讨论的“光在物质中的传播速度”无关。选项C,文章也提到了这点,没有别的物体的运行速度比光速快。选项D,光通过不同的细胞时,折射率不同,而与速度无关。因此,答案为C。
3. The result of darkness in the technique of interferometry implies that _____.
[A] there is no light passing through the sample
[B] the refractive index of the sample is very great
[C] the speed of the light passing through the sample is very low
[D] the two daughter beams weaken each other
3. 在干涉测量法中,黑暗的结果表示 _____。
[A] 没有光通过样本
[B] 样本的折射率很大
[C] 通过样本的光速很慢
[D] 两个子光束彼此削弱
答案:D 难度系数:☆
分析:推理题。根据第四段,当通过物体的光的速度减慢得越多,和另一束光束的异相程度就越大,波峰和波谷相互抵消,因此是黑暗的。因此,选项D最为符合。
4. Dr. Feld's method could be applied into identifying cancer early by _____.
[A] detecting changes of refractive indices in the components of protein factories
[B] finding out the changes of the refractive indices in some parts of the cervical-cancer cells
[C] examining the changes of the refractive indices in the nucleolus
[D] identifying the changes of the refractive indices in part of the nucleolus of the cancer cells
4. Feld博士的方法可以运用到早期发现癌症上,这要通过 _____来实现。
[A] 探测蛋白质工厂组成部分折射率的变化
[B] 发现部分子宫癌细胞中折射率的变化
[C] 探测细胞核中折射率的变化
[D] 找出部分癌细胞的细胞核中折射率的变化
答案:C 难度系数:☆☆
分析:根据第六段:They did, in a part of the cell called the nucleolus. This is the place where the components of protein factories are made. Since cancer cells grow rapidly, and thus have a high demand for proteins, it was a likely place to expect changes. 可知,Feld博士是在细胞核中发现了这种变化,因为癌细胞的生长需要大量的蛋白质,而细胞核是生产蛋白质的地方,因此,如果有变化就应该可以体现在细胞核中。所以,答案为C。
5. The best title of the passage could be _____.
[A] Image of the Transparent Cells
[B] New Technique of Celebrating Transparency
[C] Refractive Indices of the Transparent Cells
[D] New Method of Detecting Cancer Cells
5. 这篇文章最好的题目是 _____。
[A] 透明细胞的图像
[B] 研究透明的新技术
[C] 透明细胞的折射率
[D] 发现癌细胞的新方法
答案:B 难度系数:☆☆☆
分析:主旨题。这篇文章主要讲述了研究细胞折射率的新方法,通过这种新方法可以做许多研究,如细胞的样子和癌细胞的早期发现。因此,答案为B。

大多数的细胞都是透明的,也就是说,它们没有很强的反射或吸收光的能力。因此,要在显微镜下看到它们就需要一定的技巧了。许多技巧都会杀死细胞,而那些能保证它们存活的技巧只能使人们看到各个细胞的切片,而不是从三维立体的角度来观察细胞。
麻省理工大学的Michael Feld及其同事认为他们可以改变这一点。他们发明了观察活细胞的方法,而且还可以观察到立体的细胞。他们的方法叫作X线断层阶段显微法,并刊登在本周的《自然方法》上。Feld博士不是通过那些被吸收或反射的光,而是利用了细胞透明特性,观察光穿过细胞后是否发生了改变。该方法是通过测量光的折射率来实现的。
折射率测量光在某种物质中的传播速度。(光只有在真空中时才以真正的“光速”来传播,比其他任何物体的速度都要快。)虽然细胞的不同成分是透明的,却有不同的折射率。Feld博士及其研究小组因此开始寻找这些不同,希望可以通过不同的折射率来辨别细胞的各种成分。
为了估测某一细胞不同组成部分的折射率,他们使用了一种叫干涉测量的方法,将一束光线一分为二,其中一束叫作物体光束,能穿过细胞;另外一束则沿着不同的路线前进,作为参照。参照路线的长度一定,如果没有物体,那么这两个光束就会同相,与它们分开时的情况一样。两束光的波峰和波谷会互相加强,结果就是形成了非常明亮的光。通过物体的光的速度减慢得越多,两个光束异相的程度就越大。此时,波峰会与波谷重合,最终结果就是黑暗。正是因为相的变化,Feld博士的新显微形式才有了自己的名称。
但是一对光束不会制造出有用的图像来。图像的生成需要将通过物体的光束以100种不同的方式来进行扫描。从每条路径的折射率,再运用一些适当的计算,就有可能可以生成三维图像。
为了验证他的想法,Feld博士研究了子宫癌细胞。越早辨认出该细胞,病人存活的几率就越大。如果忽略了该细胞,病人就会死亡。Feld博士想知道,使用自己的新方法是否能发现癌症期间的一些变化。他们在细胞核中发现了这种变化。细胞核是生产构成蛋白质的成分的地方。因为癌细胞的生长速度极快,因此需要大量的蛋白质,所以这里是最有可能发生改变的地方。
Feld博士还计划使用不同颜色的光束,因为每种颜色在某一物质中的折射率都略有不同。这就为计算机成像提供了更多的数据,而且可能会产生更好的图像。有了足够多的图像,Feld博士的技术就可以让生物学变得透明起来,就像他研究的那些透明细胞一样。
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