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2021考研英语考前冲刺:阅读理解真题第三套(含答案)

作者: 2020-11-03 15:21 来源:长沙编辑
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  考研英语的阅读理解部分是考试的重心,也是广大学生的备考重点,而且阅读理解重视的是文章的篇章结构和上下文逻辑关系,考生可以通过对历年真题阅读理解的分析,总结出出题的思路及解题技巧。阅读理解是考研英语必出的题型,下面好轻松考研小编给大家带来了2021年考研英语阅读理解考前冲刺真题第三套(含答案),希望在最后的考研冲刺阶段对大家有帮助。


  Scientists have known for more than two decades that cancer is a disease of the genes. Something scrambles the Dna inside a nucleus, and suddenly, instead of dividing in a measured fashion, a cell begins to copy itself furiously. Unlike an ordinary cell, it never stops. But describing the process isn't the same as figuring it out. Cancer cells are so radically different from normal ones that it's almost impossible to untangle the sequence of events that made them that way. So for years researchers have been attacking the problem by taking normal cells and trying to determine what changes will turn them cancerous--always without success.


  Until now. According to a report in the current issue of Nature, a team of scientists based at M.I.T.'s Whitehead Institute for Biomedical Research has finally managed to make human cells malignant--a feat they accomplished with two different cell types by inserting just three altered genes into their DNA. While these manipulations were done only in lab dishes and won't lead to any immediate treatment, they appear to be a crucial step in understanding the disease. This is a “landmark paper,” wrote Jonathan Weitzman and Moshe Yaniv of the Pasteur Institute in Paris, in an accompanying commentary.


  The dramatic new result traces back to a breakthrough in 1983, when the Whitehead's Robert Weinberg and colleagues showed that mouse cells would become cancerous when spiked with two altered genes. But when they tried such alterations on human cells, they didn't work. Since then, scientists have learned that mouse cells differ from human cells in an important respect: they have higher levels of an enzyme called telomerase. That enzyme keeps caplike structures called telomeres on the ends of chromosomes from getting shorter with each round of cell division. Such shortening is part of a cell's aging process, and since cancer cells keep dividing forever, the Whitehead group reasoned that making human cells more mouselike might also make them cancerous.


  The strategy worked. The scientists took connective-tissue and kidney cells and introduced three mutated genes--one that makes cells divide rapidly; another that disables two substances meant to rein in excessive division; and a third that promotes the production of telomerase, which made the cells essentially immortal. They'd created a tumor in a test tube. “Some people believed that telomerase wasn't that important,” says the Whitehead's William Hahn, the study's lead author. “This allows us to say with some certainty that it is.”


  Understanding cancer cells in the lab isn't the same as understanding how it behaves in a living body, of course. But by teasing out the key differences between normal and malignant cells, doctors may someday be able to design tests to pick up cancer in its earliest stages. The finding could also lead to drugs tailored to attack specific types of cancer, thereby lessening our dependence on tissue-destroying chemotherapy and radiation. Beyond that, the Whitehead research suggests that this stubbornly complex disease may have a simple origin, and the identification of that origin may turn out to be the most important step of all.


  注(1):本文选自Time; 08/09/99, p60, 3/5p, 2c


  注(2):本文习题命题模仿对象2002年真题text 4


  1. From the first paragraph, we learn that ________________.


  [A] scientists had understood what happened to normal cells that made them behave strangely


  [B] when a cell begins to copy itself without stopping, it becomes cancerous


  [C] normal cells do no copy themselves


  [D] the DNA inside a nucleus divides regularly


  2. Which of the following statements is true according to the text?


  [A] The scientists traced the source of cancers by figuring out their DNA order.


  [B] A treatment to cancers will be available within a year or two.


  [C] The finding paves way for tackling cancer.


  [D] The scientists successfully turned cancerous cells into healthy cells.


  3. According to the author, one of the problems in previous cancer research is ________.


  [A] enzyme kept telomeres from getting shorter


  [B] scientists didn‘t know there existed different levels of telomerase between mouse cells and human cells


  [C] scientists failed to understand the connection between a cell‘s aging process and cell division.


  [D] human cells are mouselike


  4. Which of the following best defines the word “tailored” (Line 4, Paragraph 5)?


  [A] made specifically


  [B] used mainly


  [C] targeted


  [D] aimed


  5. The Whitehead research will probably result in ___________.


  [A] a thorough understanding of the disease


  [B] beating out cancers


  [C] solving the cancer mystery


  [D] drugs that leave patients less painful


  答案:B C B A D


  以上就是小编对于2021年考研英语阅读理解考前冲刺真题第三套的整理,希望大家可以好好规划下冲刺阶段的复习,有任何考研方面的问题都可以来官网咨询小编。

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