2017年7月29日雅思阅读考试真题回顾!本场雅思阅读考试中出现的三篇阅读分别为Going Bananas、The Lost
City、Thinking Small:Globalization and Choice of
Complete sentences 3题
TRUE/FALSE/NOT GIVEN 3题
A. The world’s favourite fruit could disappear forever in 10 years’ time. The banana is among the world’s oldest crops. Agricultural scientists believe that the first edible banana was discovered around ten thousand years ago. It has been at an evolutionary standstill ever since it was first propagated in the jungles of South-East Asia at the end of the last ice age. Normally the wild banana, a giant jungle herb called Musa acuminate, contains a mass of hard seeds that make the fruit virtually inedible. But now and then, hunter-gatherers must have discovered rare mutant plants that produced seed-less, edible fruits. Geneticists now know that the vast majority of these soft-fruited plants resulted from genetic accidents that gave their cells three copies of each chromosome instead of the usual two. This imbalance prevents seeds and pollen from developing normally, rendering the mutant plants sterile. And that is why some scientists believe the world’s most popular fruit could be doomed. It lacks the genetic diversity to fight off pests and diseases that are invading the banana plantations of Central America and the small-holdings of Africa and Asia alike.
B. In some ways, the banana today resembles the potato before blight brought famine to Ireland a century and a half ago. But ‘it holds a lesson for other crops, too’, says Emile Frison, top banana at the International Network for the Improvement of Banana and Plantain in Montpellier, France. ‘The state of the banana’, Frison warns, ‘can teach a broader lesson the increasing standardization of food crops round the world is threatening their ability to adapt and survive.’
C. The first Stone Age plant breeders cultivated these sterile freaks by replanting cuttings from their stems. And the descendants of those original cuttings are the bananas we still eat today. Each is a virtual clone, almost devoid of genetic diversity. And that uniformity makes it ripe for disease like no other crop on Earth. Traditional varieties of sexually reproducing crops have always had a much broader genetic base, and the genes will recombine in new arrangement in each generation. This gives them much greater flexibility in evolving responses to disease – and far more genetic resources to draw on in the face of an attack. But that advantage is fading fast, as growers increasingly plant the same few, high-yielding varieties. Plant breeders work feverishly to maintain resistance in these standardized crops. Should these efforts falter, yields of even the most productive crop could swiftly crash. ‘When some pest or disease comes along, severe epidemics can occur,’ says Geoff Hawtin, director of the Rome-based International Plant Genetic Resources Institute.
D. The banana is an excellent case in point. Until the 1950s, one variety, the Gros Michel, dominated the world’s commercial banana business. Found by French botanists in Asian the 1820s, the Gros Michel was by all accounts a fine banana, richer and sweeter than today’s standard banana and without the latter’s bitter aftertaste when green. But it was vulnerable to a soil fungus that produced a wilt known as Panama disease. ‘Once the fungus gets into the soil it remains there for many years. There is nothing farmers can do. Even chemical spraying won’t get rid of it,’ says Rodomiro Ortiz, director of the Inter-national Institute for Tropical Agriculture in Ibadan, Nigeria. So plantation owners played a running game, abandoning infested fields and moving so ‘clean’ land – until they ran out of clean land in the 1950s and had to abandon the Gros Michel. Its successor and still the reigning commercial king, is the Cavendish banana, a 19th century British discovery from southern China. The Cavendish is resistant to Panama disease and, as a result, it literally saved the international banana industry. During the 1960s, it replaced the Gros Michel on supermarket shelves. If you buy a banana today, it is almost certainly a Cavendish. But even so, it is a minority in the world’s banana crop.
NO MORE THAN THREE WORDS.
1.Banana was first eaten as a fruit by humans almost ______ years ago.
2.Banana was first planted in ______.
3.The wild banana can’t be eaten because of ______.
N.B. You may use any letter more than once.
List of People
B. David Mclaughlin
C. Emile Frison
D. Ronald Romero
E. Luadir Gasparotto
F. Geoff Hawtin
4. Pest invasion may seriously damage banana industry.
5. The effect of fungal infection in soil is often long-lasting.
6. A commercial manufacturer gave up on breeding bananas for disease resistant species. jetedu.com
7. Banana disease may develop resistance to chemical sprays.
8. A banana disease has destroyed a large number of banana plantations.
9. Consumers would not accept genetically altered crop.
10. Lessons can be learned from bananas for other crops.
11. Banana is the oldest known fruit.
12. Gros Michel is still being used as a commercial product.
13. Banana is a main food in some countries.
Summary Completion 8题
Multiple Choice 1题
The lost city
Thanks to modern remote-sensing techniques, a ruined city in Turkey is slowly revealing itself as one of the greatest and most mysterious cities of the ancient world. Sally Palmer uncovers more.
The low granite mountain, known as Kerkencs Dag, juts from the northern edge of the C'appadocian plain in Turkey. Sprawled over the mountainside are the rums of an enormous city, contained by crumbling defensive walls seven kilometers long. Many respected archaeologists believe these are the remains of the fabled city of Plena, the sixth-century BC stronghold of the Mcdes that the Greek historian Herodotus described in his famous work The Histories. The short-lived city came under Median control and only fifty years later was sacked, burned and its strong stone walls destroyed.
British archeologist Dr Geoffrey Summer has spent ten years studying the site. Excavating the ruins is a challenge because of the vast area they cover. The 7 km perimeter walls run around a site covering 271 hectares. Dr Summers quickly realised it would take far too long to excavate the site using traditional techniques alone. So he decided to use modem technology as well to map the entire site, both above and beneath the surface, to locate the most interesting areas and priorities to start digging.
In 1993. Dr Summers hired a special hand held balloon with a remote-controlled camera attached. He walked over the entire site holding the balloon and taking photos. Then one afternoon, he rented a hot-air balloon and floated over the site, taking yet more pictures By the end of the 1994 season. Dr Summers and his team had a jigsaw of aerial photographs of the whole site. The next stage was to use remote sensing, which would let them work out what lay below the intriguing outlines and ruined walls. "Archaeology is a discipline that lends itself very well to remote sensing because it revolves around space," says Scott Branting, an associated director of the project, lie started working with Dr Summers in 1995.
The project used two remote sensing techniques. The first is magnetometry which works on the principle thai magnetic fields al the surface of the Earth are influenced by what it buried beneath. It measures localised variations in the direction and intensity of this magnetic field. "The Earth's magnetic field can vary from place to place, depending on what happened there in the past." says Branting. "if something containing iron oxide was heavily burnt, by natural or human actions, the iron particles in it can be permanently reoriented, like a compass needle, to align with the Earth's magnetic field present at that point in time and space." The magnetometer detects differences in the orientations and intensities of these iron particles from the present-day magnetic field and uses them to produce an image of what lies below ground.
Kerkenes Dag lends itself particularly well to magnetometry because it was all burnt at once in a savage fire. In places the heat was sufficient to turn sandstone to glass and to melt granite. The fire was so hot that there were strong magnetic signatures set to the Earth's magnetic field from the time - around 547 BC - resulting in extremely clear pictures. Furthermore, the city was never rebuilt, "if you have multiple layers confusing picture, because you have different walls from different periods giving signatures that all go in different directions," says Branting. "We only have one going down about 1.5 meters, so we can get a good picture of this fairly short-lived city”.
Summary Completion 5题
Multiple Choice 3题
YES/NO/NOT GIVEN 6题
Thinking Small:Globalization and Choice of Technology