雅思阅读考前练习：Venus in transit

　　雅思阅读考前练习：Venus in transit!以下是

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　　Venus in transit

　　June 2004 saw the first passage, known as a ‘transit’, of the planet Venus across the face of the Sun in 122 years. Transits have helped shape our view of the whole Universe, as Heather Cooper and Nigel Henbest explain

　　A. On 8 June 2004, more than half the population of the world were treated to a rare astronomical event. For over six hours, the planet Venus steadily inched its way over the surface of the Sun. This ‘transit’ of Venus was the first since 6 December 1882. On that occasion, the American astronomer Professor Simon Newcomb led a party to South Africa to observe the event. They were based at girls’ school, where — it is alleged — the combined forces of three schoolmistresses outperformed the professionals with the accuracy of their observations.

　　B. For centuries, transits of Venus have drawn explorers and astronomers alike to the four corners of the globe. And you can put it all down to the extraordinary polymath Edmond Halley. In November 1677, Halley observed a transit of the innermost planet, Mercury, from the desolate island of St Helena in the South Pacific. He realized that, from different latitudes, the passage of the planet across the Sun’s disc would appear to differ. By timing the transit from two widely-separated locations, teams of astronomers could calculate the parallax angle — the apparent difference in position of an astronomical body due to a difference in the observer’s position. Calculating this angle would allow astronomers to measure what was then the ultimate goal: the distance of the Earth from the Sun. This distance is known as the ‘astronomical unit’ or AU.

　　C. Halley was aware that the AU was one of the most fundamental of all astronomical measurements. Johannes Kepler, in the early 17th century, had shown that the distances of the planets from the Sun governed their orbital speeds, which were easily measurable. But no-one had found a way to calculate accurate distances to the planets from the Earth. The goal was to measure the AU; then, knowing the orbital speeds of all the other planets round the Sun, the scale of the Solar System would fall into place. However, Halley realized that Mercury was so far away that its parallax angle would be very difficult to determine. As Venus was closer to the Earth, its parallax angle would be larger, and Halley worked out that by using Venus it would be possible to measure the Sun’s distance to 1 part in 500. But there was a problem: transits of Venus, unlike those of Mercury, are rare, occurring in pairs roughly eight years apart every hundred or so years. Nevertheless, he accurately predicted that Venus would cross the face of the Sun in both 1761 and 1769 — though he didn’t survive to see either.

　　D. Inspired by Halley’s suggestion of a way to pin down the scale of the Solar System, teams of British and French astronomers set out on expeditions to places as diverse as India and Siberia. But things weren’t helped by Britain and France being at war. The person who deserves most sympathy is the French astronomer Guillaume Le Gentil. He was thwarted by the fact that the British were besieging his observation site at Pondicherry in India. Fleeing on a French warship crossing the Indian Ocean, Le Gentil saw a wonderful transit — but the ship’s pitching and rolling ruled out any attempt at making accurate observations. Undaunted, he remained south of the equator, keeping himself busy by studying the islands of Maurtius and Madagascar before setting off to observe the next transit in the Philippines. Ironically after travelling nearly 50,000 kilometres, his view was clouded out at the last moment, a very dispirting experience.

　　E. While the early transit timings were as precise as instruments would allow, the measurements were dogged by the ‘black drop’ effect. When Venus begins to cross the Sun’s disc, it looks smeared not circular — which makes it difficult to establish timings. This is due to diffraction of light. The second problem is that Venus exhibits a halo of light when it is seen just outside the sun’s disc. While this showed astronomers that Venus was surrounded by a thick layer of gases refracting sunlight around it, both effects made it impossible to obtain accurate timings.

　　F. But astronomers laboured hard to analyse the results of these expeditions to observe Venus transits. Johann Franz Encke, Director of the Berlin Observatory, finally determined a value for the AU based on all these parallax measurements: 153,340,000 km. Reasonably accurate for the time, that is quite close to today’s value of 149,597,870 km, determined by radar, which has now superseded transits and all other methods in accuracy. The AU is a cosmic measuring rod, and the basis of how we scale the Universe today. The parallax principle can be extended to measure the distances to the stars. If we look at a star in January —when Earth is at one point in its orbit — it will seem to be in a different position from where it appears six months late. Knowing the width of Earth’s orbit, the parallax shift lets astronomers calculate the distance.

　　G. June 2004’s transit of Venus was thus more of an astronomical spectacle than a scientifically important event. But such transits have paved the way for what might prove to be one of the most vital breakthroughs in the cosmos — detecting Earth-sized planets orbiting other stars.

　　Questions 14-17

　　Reading Passage 2 has seven paragraphs, A-G.

　　Which paragraph contains the following information?

　　Write the correct letter, A-G, in boxes 14-17 on your answer sheet.

　　14 examples of different ways in which the parallax principle has been applied

　　15 a description of an event which prevented a transit observation

　　16 a statement about potential future discoveries leading on from transit observations

　　17 a description of physical states connected with Venus which early astronomical instruments failed to overcome

　　Questions 18-21

　　Look at the following statements (Questions 18-21) and the list of people below.

　　Match each statement with the correct person, A, B, C or D.

　　Write the correct letter, A, B, C or D, in boxes 18-21 on your answer sheet.

　　18 He calculated the distance of the Sun from the Earth based on observations of Venus with a fair degree of accuracy.

　　19 He understood that the distance of the Sun from the Earth could be worked out by comparing obsevations of a transit.

　　20 He realized that the time taken by a planet to go round the Sun depends on its distance from the Sun.

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　　21 He witnessed a Venus transit but was unable to make any calculations.

　　List of People

　　A Edmond Halley

　　B Johannes Kepler

　　C Guillaume Le Gentil

　　D Johann Franz Encke

　　Question 22-26

　　Do the following statements agree with the information given in Reading Passage 2?

　　In boxes 22-26 on your answer sheet, write

　　TRUE if the statement agrees with the information

　　FALSE if the statement contradicts the information

　　NOT GIVEN if there is no information on this

　　22 Halley observed one transit of the planet Venus.

　　23 Le Gentil managed to observe a second Venus transit.

　　24 The shape of Venus appears distorted when it starts to pass in front of the Sun.

　　25 Early astronomers suspected that the atmosphere on Venus was toxic.

　　26 The parallax principle allows astronomers to work out how far away distant stars are from the Earth.

　　以下是该篇阅读题目的答案解析：

　　Question 14

　　答案: F

　　关键词: examples of different ways, parallax principle, applied

　　定位原文: F段倒数第3句“The parallax principle can be extended…” 视差原理可以延伸应用到恒星之间距离的测量中。

　　解题思路: 句中的be extended to 就可以理解为视差原理之前是用在别的地方，现在又被延伸应用到恒星间距离的测量可以与题干中applied相对应。如果阅读得足够仔细的话，就会发现在前文中提到了利用视差原理测出了天文单位，即相当于地球到太阳的距离。可能很容易没有耐心，在看到F段之前就作出判断。比如可能会在B段倒数第四行看到parallax angle, 就简单判断该段是此题的答案;还有的可能在C段也见到了parallax一词，也就顺着作出错误判断。 因此，解答这种类型题目时候一定要有足够的耐心。故答案选F。

　　Question 15

　　答案: D

　　关键词: prevented, transit observation

　　定位原文: D段内容

　　解题思路: 该段叙述了倒霉的法国人Le Gentil两次不成功的观测经历。一次是在乘坐一艘法国军舰 穿越印度洋逃亡的时候，他看到了一次凌日现象，但是船的颠簸摇晃使他完全没有机会进行精确观测。第二次是在跋涉了将近五万公里之后到达菲律宾准备观测，但是他的视野居然被一片乌云给遮住了。由于这段文字叙述故事性较强，所以比较容易选择。该段中像ruled out，clouded out这样的词组，都能够对应题干中的prevent。最后的dispiriting experience“令人沮丧的经历”也可以体现观测受阻后的遗憾。故答案选D。

　　Question 16

　　答案： G

　　关键词： potential future discoveries

　　定位原文： G段最后1句“But such…”

　　解题思路: 如果在段落信息配对题中出现future一词，则该信息点一般都出现在文章的最后一段。本文最后一段中用pave the way for这样的词组表明transit observation的确为宇宙终极探索——寻找类地行星提供了可能性。故答案选G。

　　Question 17

　　答案： E

　　关键词： astronomical instruments, failed

　　定位原文： E段第1句“While the early transit timings…”

　　解题思路：定位句中出现的instruments和dogged与题干中的定位词分另别应。句子含义为“虽然早期对凌日时间的观测就当时所用的器材而言已足够精确,但是其测量结果却受到‘黑滴’效应的困扰。”词组be dogged by表示“为……所困扰”。这一段的确是在讲早期金星凌日观测中的不尽如人意的方面，故答案选E

　　Question 18

　　答案: D

　　关键词： Sun from Earth，observations of Venus，a fair degree of accuracy

　　定位原文： F段2、3句“Johann…”

　　解题思路: 显然对应文章F段出现的数字，通过阅读F段前五行，可以找出reasonably accurate 对应 a fair degree of accuracy, a value for the AU “天文单位的数值”， 即太阳到地球的距离，对应distance of the Sun from the Earth。所以此题应选D。

　　Question 19

　　答案: A

　　关键词： could be worked out，comparing observations of a transit

　　定位原文： B段第3句“In November…”

　　解题思路： 文中B段Hailey第一次提出通过观测凌日现象可以计算出视差角度。视差角度是指天体的位置由于观测者的位置不同而产生的明显差异。计算视差角度让 天文学家得以实现当时最终目标——算出地球与太阳之间的距离，这个距离 就是所谓的“天文单位”。

　　找到Hailey名字所在的地方，再顺着向下阅读，很容易找到答案。所以此题应选A。

　　Question 20

　　答案： B

　　关键词： time taken by a planet to go round, depends on its distance from the Sun

　　定位原文： C段第2句“Johannes Kepler, in the…”

　　解题思路： 文章中C段第二句提到了Johannes Kepler，他提出 the distances of the planets from the Sun governed their orbital speeds，其中 orbital speed 就等同于题中的 the time taken by a planet to go round the Sun。所以此题应选B。

　　Question 21

　　答案： C

　　关键词： Venus transit，make any calculations

　　定位原文： D段第5句“Fleeing on a French warship…”

　　解题思路： 倒霉的法国人Le Gentil，在出现他姓名的D段，明确提到Le Gentil saw a wonderful transit — but the ship’s pitching and rolling ruled out any attempt at making accurate observations,其中 ruled out any attempt at making accurate observations 与题目中的 unable to make any calculations相对应。所以此题应选C。

　　Question 22

　　答案： FALSE

　　关键词： Hailey, observed

　　定位原文：C段最后一句“Nevertheless, he accurately…”

　　解题思路: 定位句含义为“尽管如此，Hailey是准确预测出金星会在1761年与1769年两次穿过太阳表面，只可惜他有生之年一次也没看到。”此题考点明显，比较好定位，如果在阅读过程中对Hailey印象深刻，因此很容易看到C段最后的这句话。

　　Question 23

　　答案： FALSE

　　关键词： managed to observe, second Venus transit

　　定位原文： D段最后一句“Ironically after travelling…”

　　解题思路： D段说到在逃亡的船上，Le Gentil的第一次观测没能成功;接着他去了菲律宾， 准备第二次观测，但是对应句表明在最后一刻，天空多云，他又没成功，正好和题目中的说法相反。

　　Question 24

　　答案: TRUE

　　关键词: Venus, starts to pass in front of the Sun, appears distorted

　　定位原文: E段第2句“When Venus begins to cross…”

　　解题思路：根据句中begins to cross the Sun’s disc和题目中的starts to pass in front of the Sun相对应找到此题定位处，此时会发现对应句中的looks和题目中的appears可以完全对应，另外可以根据句中的not circular来推测前面的smear的意思，not表示转折，所以smear意思应 与circular相反，不是圆的。如果考生不认识circular,则可以通过cir这个词根来联想 circle, 进而猜测。

　　Question 25

　　答案： NOT GIVEN

　　关键词： atmosphere, Venus, toxic

　　定位原文：E段最后一句“…Venus was surrounded by…”

　　解题思路：E段倒数第二行提到 了 Venus was surrounded by a thick layer of gases,但 是这里仅仅是说金星被厚厚的大气层所围绕，并未提到这个大气层是否是toxic(有毒的)。

　　Question 26

　　答案： TRUE

　　关键词： parallax principle, distant stars

　　定位原文：F段倒数第3句“The parallax principle can be extended to measure…”

　　解题思路：The parallax principle can be extended to measure the distances to the stars.视差原理可以延伸应用到恒星之间距离的测量中。 利用parallax principle和顺序法则很容易定位此题，而且此题考点与第14题相似，不管先做哪个题目，另外一题都会很容易得出正确答案。

　　希望以上网为大家分享的雅思阅读考前练习：Venus in transit能够对大家进行雅思阅读的练习有帮助。