2011年考研英語備考：英語閱讀專項特訓(6)

　　Text 6

　　The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective and self-limiting.

　　The heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign of non-self molecules, the immune troops move quickly to eliminate the invaders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self marker. Rather, the immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non�瞫elf molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecule, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non�瞫elf molecules in the sea of microbes in which we live, learning necessitates producing the appropriate molecules and cells to match up with and counteract each non-self invader.

　　Any substance capable of stimulating an immune response is called an antigen. Tissues or cells from another individual (except an identical twin, whose cells carry identical self�瞞arkers) act as antigens; because the immune system recognizes transplanted tissues as foreign, it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestive system into their primary, non�瞐ntigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which stick out from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface, some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack.

　　The result can be so-called autoimmune disease. The painful side effects of those diseases are caused by a person’s immune system actually attacking itself. (427 words)

　　1. We know from the passage that the immune system _______________

　　[A] is no less complicated than the nervous system.

　　[B] far exceeds the human brain in intricacy.

　　[C] is enclosed by numerous sensitive cells.

　　[D] results in an effective communications network.

　　2. The principal task of the immune system is to _______________

　　[A] recognize and eliminate all foreign molecules that enter the body.

　　[B] remove all the substances that invade the body organisms.

　　[C] defend the body from the attacks of different viruses and bacteria.

　　[D] identify and specify all non�瞫elf molecules it encounters.

　　3. The remembering power of a person’s immune system is _______________

　　[A] mostly descended from his/her ancestors.

　　[B] partially passed down from his/her mother.

　　[C] mainly acquired through fighting against foreign cells.

　　[D] basically generated by its communications network.

　　4. Which of the following is NOT true according to the passage?

　　[A] A tissue transplanted from father to daughter would be less acceptable than that transplanted between twins.

　　[B] The immune system would never wrongly identify self as non�瞫elf and execute a misdirected immune attack.

　　[C] When a normally functioning immune system attacks a non�瞫elf molecule, the system will remember the specifics of the foreign body.

　　[D] The immune cells and other body cells can coexist peaceably in a state known as self�瞭olerance.

　　5. The main idea of the passage may be generalized as_______________

　　[A] the success of the immune system in distinguishing foreign substances.

　　[B] the normal and abnormal activities of the immune system in the body.

　　[C] the unfavorable effects of the immune system on organ transplantation.

　　[D] the essential duties of the immune system in guarding the body.

　　核心詞匯

　　intricacy n. 錯綜復雜的事物;紛繁難懂之處

　　dynamic a. 動態的,有動力的,有力的

　　back and forth來回地,反復地

　　hive n. 蜂房,蜂箱

　　organism n. 生物體,有機體

　　molecule n.分子

　　tissue n. (動、植物的)組織;薄的紗織品

　　antigen n. 抗原

　　epitome n. 摘要,縮影,化身

　　microbe n. 微生物,細菌

　難句剖析

　　1. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective and self-limiting.

　　【解析】 句子的主干是The result is a sensitive system of checks and balances。that引導定語從句。

　　【譯文】 這就創造了一個靈敏的檢測和平衡系統，它可以快速、及時、有效和自我限制的產生免疫響應。

　　2. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non�瞫elf molecules in the sea of microbes in which we live, learning necessitates producing the appropriate molecules and cells to match up with and counteract each non-self invader.

　　【解析】 本句子的主干是your immune system must learn from experience…。Despite 引導讓步狀語，with引導的短語作狀語，in which引導定語從句，learning引導后置定語，主語是your immune system，match up 和諧，相配。

　　【譯文】 盡管病毒可能來自家族，但是人的免疫系統必須從實踐中學習如何在人類所生活的充滿微生物的世界里去分解那些大量異己，并創造出相應的分子或者細胞來對付它們。

　　3. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack.

　　【解析】 這是一個倒裝句，only位于句首修飾狀語，強調in abnormal situations。identify…as 把……認為……。

　　【譯文】 只有在不正常的情況下，免疫系統才會錯把自我當成異己并執行錯誤的進攻。

　　文章類型： 科普類——人體免疫細胞

　　本文主要介紹了免疫系統保護人體的功能，并對免疫系統的復雜性和抗原做了說明。當免疫細胞遇到攜帶外來的分子或者異己分子的細胞或者組織時，會進行攻擊和消滅它們。

　　試題解析

　　1. 從文中可知，免疫系統_______________

　　[A] 不亞于神經系統復雜。

　　[B] 遠比人腦復雜。

　　[C] 被無數敏感細胞包圍。

　　[D] 是一個有效的通訊網絡。

　　細節事實題【正確答案】[B]

　　原文對應信息是第一段第一句The immune system is equal in complexity to the combined intricacies of the brain and nervous system.(免疫系統的復雜性等于大腦與神經系統的復雜性之總和。)

　　2. 免疫系統的主要任務是_______________

　　[A] 識別、消滅侵入體內的異己細胞。

　　[B] 移除入侵體內的所有物質。

　　[C] 保護身體免受不同病毒和細菌的攻擊。

　　[D] 識別和認定它碰到的所有細胞。

　　細節事實題【正確答案】[A]

　　原文對應信息是第二段第一、二句The heart of the immune system is the ability to distinguish between self and non�瞫elf. When immune defenders encounter cells or organisms carrying foreign of non�瞫elf molecules, the immune troops move quickly to eliminate the invaders.(免疫系統的核心是自我與異己的識別能力。當免疫細胞遇到攜帶外來分子或異己分子的細胞或組織時，這些免疫細胞會行動迅速，消滅那些入侵者。)

　　3. 一個人的免疫細胞記憶能力是_______________

　　[A] 大多數繼承了她或他的祖先。

　　[B] 部分遺傳于他或她的媽媽。

　　[C] 主要通過與外部細胞斗爭獲得。

　　[D] 基本通過它的通訊網絡產生。

　　細節事實題【正確答案】[C]

　　原文對應信息是第二段比較后一句your immune system must learn from experience with the many millions of distinctive non�瞫elf molecules…and cells to match up with and counteract each non�瞫elf invader.(但是人的免疫系統必須從實踐中學習如何在人類所生活的充滿微生物的世界里去分解那些大量異己，并創造出相應的分子或者細胞來對付它們。)可知，它的記憶能力是通過與外部細胞斗爭而得到的。

　　4. 根據所給材料,下面哪種說法是錯誤的?

　　[A] 動植物組織在父女之間的移植沒有雙胞胎之間的移植容易接納。

　　[B] 免疫系統不會錯把自我當成異己并執行錯誤的進攻。

　　[C] 一個正常運轉的免疫系統在攻擊一個異己分子時，可以記憶這個異己分子的全部細節。

　　[D] 人體的免疫細胞和其他體細胞能夠在一種叫做自體耐受性的狀態下和平共處。

　　細節事實題【正確答案】[B]

　　原文對應信息是第三段比較后一句Only in abnormal situations does the immune system wrongly identify self as non�瞫elf and execute a misdirected immune attack.(只有在不正常的情況下，免疫系統才會錯把自我當成異己并執行錯誤的進攻。)而其他三項文中都有提到，故可排除。

　　5. 本文主要講的是_______________

　　[A] 免疫細胞成功的區分外部物質。

　　[B] 體內免疫細胞的正常和非正常的活動。

　　[C] 器官移植方面免疫細胞的不利影響。

　　[D] 免疫細胞保護身體的基本責任。

　　中心主旨題【正確答案】[D]

　　第一段講免疫系統復雜性，第二段著重介紹了免疫系統的任務、識別能力、記憶能力，并排斥來自其他組織或細胞，總體來看主要講的是免疫細胞保護身體的功能。

　　全文精譯

　　免疫系統的復雜性相當于大腦和神經系統的復雜性之和。免疫系統之所以能成功的保衛身體就在于它擁有一個由數百萬個細胞組成的可動態調整的通信網。這些細胞組成人體的各種組織，然后像蜂群圍繞蜂巢一樣來回往復的傳遞信息，這就創造了一個靈敏的檢測和平衡系統，它可以快速、及時、有效和自我限制的產生免疫響應。

　　免疫系統的核心是自我與異己的識別能力。當免疫細胞遇到攜帶外來分子或異己分子的細胞或組織時，這些免疫細胞會行動迅速，消滅那些入侵者。事實上，每一個人的體細胞都有自己獨特的分子，視為自我。人體的免疫細胞通常是不攻擊那些帶有自我標記的組織的。并且人體的免疫細胞和其他體細胞是可以在一種叫做自體耐受性的狀態下和平共處的。一個正常運轉的免疫系統在攻擊一個異己分子時，可以記憶這個異己分子的全部細節。以后再遇到同種異己分子時，免疫系統就可以有針對性的做出反應。由于在哺乳期可能會出現抗體的例外情況，因此這種所謂的免疫系統的記憶能力不是通過遺傳得到的。盡管病毒可能來自家族，但是人的免疫系統必須從實踐中學習如何在人類所生活的充滿微生物的世界里去分解那些大量異己，并創造出相應的分子或者細胞來對付它們。

　　任何能引起免疫反應的物質都被稱為抗原。任何來自其他個體的組織或細胞都是抗原，同源雙胞胎除外，因為他們帶有同源標記。由于免疫系統把移植過來的組織和細胞視為異己，因此總是排斥它們。如果營養蛋白不首先被消化系統分解成原始的非抗原性的高分子鏈節，身體甚至也將會拒絕這些營養蛋白。抗原的表面有一種突起，從這種突起不同的復雜外形就可以分辨出是否為外來異己。大多數抗原，即使是比較簡單的微生物，在其表面也會帶有很多種不同的這類突起，有的甚至有上百種。這些突起更容易引起免疫反應。只有在不正常的情況下，免疫系統才會錯把自我當成異己并執行錯誤的進攻。

　　這就是一種被稱為自體免疫的疾病。這種病的痛楚在于這是人類免疫系統的自我攻擊。

　　第一段：免疫系統的復雜性。

　　第二段：免疫系統的識別能力。

　　第三段：免疫系統排斥任何來自其他個體的組織或細胞。

　　第四段：給出全篇文章的結論。