TEXT EIGHT
A boy or a girl? That is usually the first question asked when a woman gives birth. Remarkably, the answer varies with where the mother lives. In rich countries the chances of its being a boy are about 5% higher than in poor ones. Equally remarkably, that figure has been falling recently. Several theories have been put forward to explain these observations. Some argue that smoking plays a role, others that diet may be important. Neither of these ideas has been supported by evidence from large studies. But new research points to a different factor: stress.
Strange as it might seem, the terrorist attacks of September 11th 2001 shed light on the enigma. Studies noting the sex of babies conceived in New York during the week of the attacks found a drop in the ratio of males to females. That is consistent with earlier studies, which revealed a similar shift in women who became pregnant during floods and earthquakes and in time of war. Moreover, a study carried out eight years ago by researchers at the University of Aarhus, in Denmark, revealed that women who suffered the death of a child or spouse from some catastrophic illness around the time they conceived were much more likely to give birth to girls than to boys.
Taken together, these results suggest that acute stress to a woman at the time of conception shifts the sex ratio towards girls. However, Carsten Obel, a researcher at Aarhus who was not involved in the earlier study, wondered if the same might be true of chronic stress too. In a paper just published in Human Development, he shows that it is.
Dr Obel used a set of data collected between 1989 and 1992. During that period 8,719 expectant mothers were asked to fill in questionnaires that inquired, among other things, about their level of stress. Dr Obel found that the more stressed a mother had been, the less chance she had of having given birth to a boy. Only 47% of children born to women in the top quartile of stress were males. That compared with 52% for women in the bottom quartile. Dr Obel suspects the immediate cause is that male pregnancies are more likely to miscarry in response to stress than female pregnancies are, especially during the first three months. However, that is difficult to prove. More intriguing, though, is the ultimate cause, for he thinks it might be adaptive, rather than pathological.
That is because the chances are that a daughter who reaches adulthood will find a mate and thus produce grandchildren. A son is a different matter. Healthy, strapping sons are likely to produce lots of grandchildren, by several women—or would have done in the hunter-gatherer societies in which most human evolution took place. Weak ones would be marginalised and maybe even killed in the cut and thrust of male competition. If a mother's stress adversely affects the development of her fetus then selectively aborting boys, rather than wasting time and resources on bringing them to term, would make evolutionary sense.
That, in turn, would explain why women in rich countries, who are less likely to suffer from hunger and disease, are more likely to give birth to sons. That this likelihood is, nevertheless, falling suggests that rich women's lives may be more stressful than they used to be.
1. The author begins the passage by_____
[A] presenting an argumentation.
[B] explaining a phenomenon.
[C] raising a question.
[D] making a comparison
2. The ratio of giving birth to a boy is falling in rich countries because_____
[A] the terrorist attacks of September 11th 2001 exerted huge negative impact.
[B] women are facing greater pressure than past.
[C] women are under new pressure now which they seldom faced in the past.
[D] male pregnancies are more easily to miscarry.
3. Which of the following can explain Dr Obel’s opinion that the ultimat cause is adaptive rather than pathological?
[A] 47% of children born to women in the top quartile of stress were males while 52% in the bottom quartile.
[B] Women in rich countries are more likely to give birth to boys.
[C] Women selectively abort boys rather than waste time and resources on bringing them to term for fear of male competition.
[D] Women who suffer from calamity in conception are more likely to give birth to girls.
4. Women in the hunter-gatherer societies are more likely to give birth to daughters because_____
[A] they agree that giving birth to daughters is beneficial in the evolutionary sense.
[B] sons are likely to produce lots of grandchildren with several women.
[C] they think it is a better practice for a daughter to produce grandchildren with only one mate.
[D] they think bringing sons to term is wasting time and resources.
5.From this passage, we may draw a conclusion that_____
[A] acute stress is more likely to cause women to choose aborting boys than chronic stress.
[B] stress to a woman at the time of conception, whether acute or chronic, will shift the sex ratio towards girls.
[C] more girls will be born in the future because today’s women, in both rich and poor countries, suffer from increasing pressure.
[D] chronic stress is more decisive in influencing the women’s pregnancies.
文章剖析：
这篇文章是介绍影响婴儿出生性别原因的一个新的研究成果--压力。文章第一段提出以往人们对该问题的看法，然后引出新的研究结果;第二段用一些事例来证明突发压力对于婴儿性别的影响;第三段、第四段讲述Obel博士调查研究表明慢性压力在这方面的影响;第五段对Obel博士的研究结果作了一些论证;第六段是对第一段提到的现象用得出的结论做解释。
词汇注释：
enigma n. 谜
conception n. 受精
chronic adj. 长期的，持续的
questionnarie n. 调查表
quartile n. 四分位值
miscarry v. 流产
pathological adj. 病理的
strapping adj. 伟岸的，魁梧的
fetus n. 胎儿
难句突破：
(1) Moreover, a study carried out eight years ago by researchers at the University of Aarhus, in Denmark, revealed that women who suffered the death of a child or spouse from some catastrophic illness around the time they conceived were much more likely to give birth to girls than to boys.
[主体句式] A study revealed that…
[结构分析]这是一个复合句，主语后面是一个过去分词短语做定语;revealed后面的宾语从句比较复杂，从句的主体句式为women or spouse were likely to …，状语中that 引导的定语从句用来修饰time, 第一个主语women后有一个以who引导的定语从句。
[句子译文] 而且，八年前奥尔胡斯大学研究者们做的一项研究也表明，经过头胎死亡经历或配偶在其怀孕期间患上一些灾难性疾病的妇女更有可能生女孩。
(2) If a mother's stress adversely affects the development of her fetus then selectively aborting boys, rather than wasting time and resources on bringing them to term, would make evolutionary sense.
[主体句式] If… then selectively aborting boys…would make sense.
[结构分析] 这是一个带有条件状语从句的复合句，主语由现在分词短语构成。
[句子译文] 如果母亲受到的压力对胎儿发展起到相反作用，选择性地将男孩流产，而不是浪费时间和资源将他们养大，这从进化意义上说得通的。
题目分析:
[答案]A
[难度系数] ☆
[分析]推理题。作者在文章一开始就指出在富裕国家中妇女生男孩的比率比贫穷国家高出5%，但目前这个比率在下降，有许多人给出自己的解释，但都不能被大型的研究所证明，而现在又有新的论点，就是压力的作用。接下来的几段就是对这个论点的证实。可见，作者是以提出一个论点的形式来开始这篇文章的。
[答案]B
[难度系数] ☆☆☆
[分析]推理题。首先A选项明显是错误的，因为这个影响只限于美国，并不包括所有的富裕国家。D也是错误选项，因为文章第四段中提到了这一点，但是选项中却丢掉了一个重要前提，也就是在较大的压力下，怀了男孩的女性才更加容易流产。题干要求找出富裕国家目前男孩出生率下降的原因，文章整篇都在讨论压力对于婴儿性别的作用，而最后一段的最后一句话作者指出，目前这个比率下降可能是因为富裕国家妇女现在承受的压力要比以前多，但是没有说明有新的压力。因此，答案为B。
[答案]C
[难度系数] ☆☆☆
[分析]细节题。第四段中提到，Obel博士认为导致女性在面临压力时生女孩的几率更大，其根本原因应该是适应性的原因而不是生理性原因。第四段提到，Obel怀疑是其直接原因是面临压力时如果怀孕的是男孩那么就更容易流产。紧接着第五段就给出了解释，那就是在资源紧缺的男性竞争社会中，弱小的男性更容易被边缘化，被淘汰，而女性则不存在这个问题，所以面对这种压力，妇女生育孩子时会选择将男婴流产，这是一种适应环境的做法。因此，答案中C是可以说明他的这个观点的，A、B、D只是一些表象。
[答案]D
[难度系数] ☆☆☆
[分析]推理题。文章第五段指出在原始狩猎社会中，健康、强壮的男性可以和几位女性一起繁殖许多后代，而弱小的则会被边缘化甚至在男性竞争中被杀死。妇女在生育孩子时就会面临这样的压力，她更情愿将男婴流产，也不愿意花费了如此多的时间和精力后将男婴生出来，却面临被淘汰的压力。因此，在原始狩猎社会中，女孩出生率较高的原因是因为妇女生育时面临的这种压力。选项中，D为正确答案。A选项显然是错误的，原始人不会以进化的观点去思考问题。B选项的说法只是一个现象，并不是题干的原因。C选项的说法与原文相反。
[答案]B
[难度系数] ☆☆☆
[分析] 推理题。题干要求根据整篇文章推导出一个结论，本文主要讲述了压力对于婴儿出生性别的影响，分别用一些数据和事实证明突发压力和慢性压力都有一定的影响，从中可以得出结论，就是突发与急性压力都会使得女孩出生率高一些。答案A、D文中并没有进行比较、缺少证据，C的内容也文中也没有提到。因此，正确答案为B。
参考译文：
男孩还是女孩?这通常是一个女人生完孩子后问的第一个问题。很显然的，因为这位母亲所在的地方不同答案也就不同。在富裕国家中生男孩的比率要比贫穷国家高5%。同样引人注目的是，最近这个数字有所降低。人们提出了几个理论来解释这些现象。有人认为吸烟可能是原因所在，也有人认为节食的影响较大。但大规模研究的证据却都不支持这两个观点，而新的研究指出了另外一个因素：压力。
虽然看起来很奇怪，但2001年“9·11”恐怖袭击揭示了这个问题的谜底。对恐怖袭击的那一周在纽约出生婴儿的性别研究发现男女性别比例下降了，这与早期的研究一致。早期研究表明洪水、地震和战争期间怀孕妇女生育男女的比例也有相似的变化。而且，八年前奥尔胡斯大学研究者们做的一项研究也表明，经过头胎死亡经历或配偶在其怀孕期间患上一些灾难性疾病的妇女更有可能生女孩。
综合这些研究结果表明女性在受精时如果受到突然的压力，那么生女孩的比例就会增大。但是，奥尔胡斯的一位研究者CarstenObel并没有参与早期的研究，他怀疑持续的压力是否也会有同样的影响。他刚刚在《人类发展》上发表的一篇论文表明事实确实如此。
Obel博士使用了1989年至1992年间的一组数字。在这个时期，8791名妇女受邀填写问卷调查，调查其中一项就是她们压力程度。Obel博士发现一个妇女承受的压力越重，她生男孩的概率就越小。压力最大的四成妇女只有47%生育男孩，而最小的四成妇女比例为52%。Obel博士怀疑这种现象的直接原因是在压力的情况下，怀男婴的妇女比怀女婴的妇女更容易流产，尤其是在前三个月。这一点很难证实。更让人迷惑的是他认为根本原因是适应性的而不是生理性的。
这是因为可能的情况是女孩成年后就要找一位男性，然后生育后代。而男孩则不一样。健康、魁梧的男性更有可能与几位女性生育很多后代，至少在原始狩猎族社会是这样的，大多数人类进化就是这样进行的。弱小的将会被边缘化，甚至有可能在男性的竞争性打斗中被杀死。如果母亲受到的压力对胎儿发展起到相反作用，选择性地将男孩流产，而不是浪费时间和资源将他们养大，这从进化意义上说得通的。
这反过来也可以解释为什么在富裕国家中女性很少受到饥饿和疾病的威胁，更容易生育男孩。尽管存在这种可能，但是数据的下降说明富裕女性目前所受的压力要比以前大得多。
