第一篇：

　　内向和外向型人格

　　有两个小孩，一个对新事物感兴趣，一个对新事物感到害怕。然后说他们大脑的结构(还是分泌物?)是不一样的。有些人长大后保持了他原本的性格，有些人会改变。最后说家长的影响也会改变孩子的性格。从很多方面来说说明小孩子的这种性格是可以改变的，基本上和先天的无关。如果后天父母故意的培养小孩子这种大胆的能力，小孩子也可以从孤僻变为活泼

　　解析：

　　该文章为心理学类文章。心理学类文章的重点在于描述因果关系的理解，本篇文章的重点在于理解对于婴儿性格的描述以及与婴儿性格受到哪些因素的影响。以下是关于婴儿性格影响的因素以及大脑在整个过程中所起作用的描述。

　　extraversion and introversion

　　eysenck's theory

　　hans eysenck described extraversion-introversion as the degree to which a person is outgoing and interactive with other people. these behavioral differences are presumed to be the result of underlying differences in brain physiology. extroverts seek excitement and social activity in an effort to heighten their arousal level, whereas introverts tend to avoid social situations in an effort to keep such arousal to a minimum. eysenck designated extraversion as one of three major traits in his p-e-n model of personality, which also includes psychoticism and neuroticism.

　　eysenck originally suggested that extraversion was a combination of two major tendencies, impulsiveness and sociability. he later added several other more specific traits, namely liveliness, activity level, and excitability. these traits are further linked in his personality hierarchy to even more specific habitual responses, such as partying on the weekend.

　　eysenck compared this trait to the four temperaments of ancient medicine, with choleric and sanguine temperaments equating to extraversion, and melancholic and phlegmatic temperaments equating to introversion.

　　biological factors

　　the relative importance of nature versus environment in determining the level of extraversion is controversial and the focus of many studies. twin studies find a genetic component of 39% to 58%. in terms of the environmental component, the shared family environment appears to be far less important than individual environmental factors that are not shared between siblings.

　　eysenck proposed that extraversion was caused by variability in cortical arousal. he hypothesized that introverts are characterized by higher levels of activity than extroverts and so are chronically more cortically aroused than extroverts. the fact that extroverts require more external stimulation than introverts has been interpreted as evidence for this hypothesis. other evidence of the "stimulation" hypothesis is that introverts salivate more than extroverts in response to a drop of lemon juice.

　　extraversion has been linked to higher sensitivity of the mesolimbic dopamine system to potentially rewarding stimuli. this in part explains the high levels of positive affect found in extroverts, since they will more intensely feel the excitement of a potential reward. one consequence of this is that extroverts can more easily learn the contingencies for positive reinforcement, since the reward itself is experienced as greater.

　　one study found that introverts have more blood flow in the frontal lobes of their brain and the anterior or frontal thalamus, which are areas dealing with internal processing, such as planning and problem solving. extroverts have more blood flow in the anterior cingulate gyrus, temporal lobes, and posterior thalamus, which are involved in sensory and emotional experience. this study and other research indicates that introversion-extraversion is related to individual differences in brain function.

　　第二篇：

　　comet

　　彗星的核很小，但是它的外层光亮部分很大，有的甚至超过太阳。它的尾巴是受太阳的作用力被吹出来的。

　　彗星每次经过太阳都会被吹出一部分物质，所以一般绕日不到一百次就消亡了。

　　大部分彗星来自比冥王星还远的一块区域。它们本来是一些小行星，当相互碰撞或受到冥王星的引力后，它们就脱离了原来的轨道变成了靠近太阳系中心的彗星。

　　免不了的，最后提到了哈雷彗星，76年一次。然后提到中国人从公元前开始就连续记录了30次哈雷彗星的出现。

　　解析：该篇文章属于典型est的常考文章类型。关于天文学的文章重点在于考生要处理大量生词以及相关概念在原文中描述的理解。以下是来自wiki对于彗星，哈雷彗星以及相关概念的解释。

　　comet

　　a comet is an icy small solar system body (sssb) that, when close enough to the sun, displays a visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a tail. these phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet. comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. comets have been observed since ancient times and have traditionally been considered bad omens.

　　comets have a wide range of orbital periods, ranging from a few years to hundreds of thousands of years. short-period comets originate in the kuiper belt, or its associated scattered disc, which lie beyond the orbit of neptune. longer-period comets are thought to originate in the oort cloud, a hypothesized spherical cloud of icy bodies in the outer solar system. long-period comets plunge towards the sun from the oort cloud because of gravitational perturbations caused by either the massive outer planets of the solar system (jupiter, saturn, uranus, and neptune), or passing stars. rare hyperbolic comets pass once through the inner solar system before being thrown out into interstellar space along hyperbolic trajectories.

　　comets are distinguished from asteroids by the presence of a coma or a tail. however, extinct comets that have passed close to the sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids. asteroids are thought to have a different origin from comets, having formed inside the orbit of jupiter rather than in the outer solar system. the discovery of main-belt comets and active centaurs has blurred the distinction between asteroids and comets (see asteroid terminology).

　　halley's comet or comet halley is the best-known of the short-period comets, and is visible from earth every 75╟76 years. halley is the only short-period comet that is clearly visible to the naked eye from earth, and thus the only naked-eye comet that might appear twice in a human lifetime.[11] other naked-eye comets may be brighter and more spectacular, but will appear only once in thousands of years.

　　halley's returns to the inner solar system have been observed and recorded by astronomers since at least 240 bce. clear records of the comet's appearances were made by chinese, babylonian, and medieval22 european chroniclers, but were not recognized as reappearances of the same object at the time. the comet's periodicity was first determined in 1705 by english astronomer edmond halley, after whom it is now named. halley's comet last appeared in the inner solar system in 1986 and will next appear in mid-2061.

　　第三篇：

　　nile river

　　尼罗河农业的发展，和撒哈拉沙漠对比，主要是讲人口往非洲南迁，本来以为作物大多在平原。后卫发现竟然在撒哈拉干旱贫瘠的地区。在冰川什么时期前，撒哈拉有草有树，之后人们打狼，为了保护农作物。同时期猎杀小动物，像鸟，捕鱼，之后就以农业为主了。

　　撒哈拉以前是绿洲，后来变成了沙漠，于是人们都就移居到了尼罗河附近。

　　尼罗河经常泛滥。那时候他们就暂时移居到附近的绿洲。

　　他们种庄稼，养牲畜。尽管农业是从东方起源的，但是尼罗河附近的农业物种源自非洲南部。

　　解析：本篇文章讲解尼罗河地区农业的特点，文章的重点在于理解造成农业发展的原因，类似讲解农业发展原因的文章可以参照tpo阅读文章the origins of agriculture。同时文章给出关于尼罗河和沙漠的比较和对比。以下为对于尼罗河地区农业的特点的介绍。

　　nile river

　　the greek historian herodotus wrote that "egypt was the gift of the nile". an unending source of sustenance, it provided a crucial role in the development of egyptian civilization. silt deposits from the nile made the surrounding land fertile because the river overflowed its banks annually. the ancient egyptians cultivated and traded wheat, flax, papyrus and other crops around the nile. wheat was a crucial crop in the famine-plagued middle east. this trading system secured egypt's diplomatic relationships with other countries, and contributed to economic stability. far-reaching trade has been carried on along the nile since ancient times. the ishango bone is probably an early tally stick. it has been suggested that this shows prime numbers and multiplication, but this is disputed. in the book how mathematics happened: the first 50,000 years, peter rudman argues that the development of the concept of prime numbers could only have come about after the concept of division, which he dates to after 10,000 bc, with prime numbers probably not being understood until about 500 bc. he also writes that "no attempt has been made to explain why a tally of something should exhibit multiples of two, prime numbers between 10 and 20, and some numbers that are almost multiples of 10." it was discovered along the headwaters of the nile (near lake edward, in northeastern congo) and was carbon-dated to 20,000 bc.

　　water buffalo were introduced from asia, and assyrians introduced camels in the 7th century bc. these animals were killed for meat, and were domesticated and used for ploughing—or in the camels' case, carriage. water was vital to both people and livestock. the nile was also a convenient and efficient means of transportation for people and goods. the nile was an important part of ancient egyptian spiritual life. hapy was the god of the annual floods, and both he and the pharaoh were thought to control the flooding. the nile was considered to be a causeway from life to death and the afterlife. the east was thought of as a place of birth and growth, and the west was considered the place of death, as the god ra, the sun, underwent birth, death, and resurrection each day as he crossed the sky.