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　　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(fù)雜的事物;紛繁難懂之處

　　dynamic a. 動態(tài)的,有動力的,有力的

　　back and forth來回地,反復(fù)地

　　hive n. 蜂房,蜂箱

　　organism n. 生物體,有機(jī)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(xì)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(dǎo)定語從句。

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

　　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(dǎo)讓步狀語，with引導(dǎo)的短語作狀語，in which引導(dǎo)定語從句，learning引導(dǎo)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(tǒng)必須從實踐中學(xué)習(xí)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(chuàng)造出相應(yīng)的分子或者細(xì)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(qiáng)調(diào)in abnormal situations。identify…as 把……認(rèn)為……。

　　【譯文】 只有在不正常的情況下，免疫系統(tǒng)才會錯把自我當(dāng)成異己并執(zhí)行錯誤的進(jìn)攻。

　　文章類型： 科普類——人體免疫細(xì)胞

　　本文主要介紹了免疫系統(tǒng)保護(hù)人體的功能，并對免疫系統(tǒng)的復(fù)雜性和抗原做了說明。當(dāng)免疫細(xì)胞遇到攜帶外來的分子或者異己分子的細(xì)胞或者組織時，會進(jìn)行攻擊和消滅它們。

　　試題解析

　　1. 從文中可知，免疫系統(tǒng)_______________

　　[A] 不亞于神經(jīng)系統(tǒng)復(fù)雜。

　　[B] 遠(yuǎn)比人腦復(fù)雜。

　　[C] 被無數(shù)敏感細(xì)胞包圍。

　　[D] 是一個有效的通訊網(wǎng)絡(luò)。

　　細(xì)節(jié)事實題【正確答案】[B]

　　原文對應(yīng)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(tǒng)的復(fù)雜性等于大腦與神經(jīng)系統(tǒng)的復(fù)雜性之總和。)

　　2. 免疫系統(tǒng)的主要任務(wù)是_______________

　　[A] 識別、消滅侵入體內(nèi)的異己細(xì)胞。

　　[B] 移除入侵體內(nèi)的所有物質(zhì)。

　　[C] 保護(hù)身體免受不同病毒和細(xì)菌的攻擊。

　　[D] 識別和認(rèn)定它碰到的所有細(xì)胞。

　　細(xì)節(jié)事實題【正確答案】[A]

　　原文對應(yīng)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(tǒng)的核心是自我與異己的識別能力。當(dāng)免疫細(xì)胞遇到攜帶外來分子或異己分子的細(xì)胞或組織時，這些免疫細(xì)胞會行動迅速，消滅那些入侵者。)

　　3. 一個人的免疫細(xì)胞記憶能力是_______________

　　[A] 大多數(shù)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(xì)胞斗爭獲得。

　　[D] 基本通過它的通訊網(wǎng)絡(luò)產(chǎn)生。

　　細(xì)節(jié)事實題【正確答案】[C]

　　原文對應(yīng)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(tǒng)必須從實踐中學(xué)習(xí)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(chuàng)造出相應(yīng)的分子或者細(xì)胞來對付它們。)可知，它的記憶能力是通過與外部細(xì)胞斗爭而得到的。

　　4. 根據(jù)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(tǒng)不會錯把自我當(dāng)成異己并執(zhí)行錯誤的進(jìn)攻。

　　[C] 一個正常運轉(zhuǎn)的免疫系統(tǒng)在攻擊一個異己分子時，可以記憶這個異己分子的全部細(xì)節(jié)。

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

　　細(xì)節(jié)事實題【正確答案】[B]

　　原文對應(yīng)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(tǒng)才會錯把自我當(dāng)成異己并執(zhí)行錯誤的進(jìn)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(xì)胞成功的區(qū)分外部物質(zhì)。

　　[B] 體內(nèi)免疫細(xì)胞的正常和非正常的活動。

　　[C] 器官移植方面免疫細(xì)胞的不利影響。

　　[D] 免疫細(xì)胞保護(hù)身體的基本責(zé)任。

　　中心主旨題【正確答案】[D]

　　第一段講免疫系統(tǒng)復(fù)雜性，第二段著重介紹了免疫系統(tǒng)的任務(wù)、識別能力、記憶能力，并排斥來自其他組織或細(xì)胞，總體來看主要講的是免疫細(xì)胞保護(hù)身體的功能。

　　全文精譯

　　免疫系統(tǒng)的復(fù)雜性相當(dāng)于大腦和神經(jīng)系統(tǒng)的復(fù)雜性之和。免疫系統(tǒng)之所以能成功的保衛(wèi)身體就在于它擁有一個由數(shù)百萬個細(xì)胞組成的可動態(tài)調(diào)整的通信網(wǎng)。這些細(xì)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(fù)的傳遞信息，這就創(chuàng)造了一個靈敏的檢測和平衡系統(tǒng)，它可以快速、及時、有效和自我限制的產(chǎn)生免疫響應(yīng)。

　　免疫系統(tǒng)的核心是自我與異己的識別能力。當(dāng)免疫細(xì)胞遇到攜帶外來分子或異己分子的細(xì)胞或組織時，這些免疫細(xì)胞會行動迅速，消滅那些入侵者。事實上，每一個人的體細(xì)胞都有自己獨特的分子，視為自我。人體的免疫細(xì)胞通常是不攻擊那些帶有自我標(biāo)記的組織的。并且人體的免疫細(xì)胞和其他體細(xì)胞是可以在一種叫做自體耐受性的狀態(tài)下和平共處的。一個正常運轉(zhuǎn)的免疫系統(tǒng)在攻擊一個異己分子時，可以記憶這個異己分子的全部細(xì)節(jié)。以后再遇到同種異己分子時，免疫系統(tǒng)就可以有針對性的做出反應(yīng)。由于在哺乳期可能會出現(xiàn)抗體的例外情況，因此這種所謂的免疫系統(tǒng)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(tǒng)必須從實踐中學(xué)習(xí)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(chuàng)造出相應(yīng)的分子或者細(xì)胞來對付它們。

　　任何能引起免疫反應(yīng)的物質(zhì)都被稱為抗原。任何來自其他個體的組織或細(xì)胞都是抗原，同源雙胞胎除外，因為他們帶有同源標(biāo)記。由于免疫系統(tǒng)把移植過來的組織和細(xì)胞視為異己，因此總是排斥它們。如果營養(yǎng)蛋白不首先被消化系統(tǒng)分解成原始的非抗原性的高分子鏈節(jié)，身體甚至也將會拒絕這些營養(yǎng)蛋白。抗原的表面有一種突起，從這種突起不同的復(fù)雜外形就可以分辨出是否為外來異己。大多數(shù)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(yīng)。只有在不正常的情況下，免疫系統(tǒng)才會錯把自我當(dāng)成異己并執(zhí)行錯誤的進(jìn)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(tǒng)的自我攻擊。

　　第一段：免疫系統(tǒng)的復(fù)雜性。

　　第二段：免疫系統(tǒng)的識別能力。

　　第三段：免疫系統(tǒng)排斥任何來自其他個體的組織或細(xì)胞。

　　第四段：給出全篇文章的結(jié)論。