英语六级冲刺阅读训练及答案(20篇).doc

1、一The Earth comprises three principal layers: the dense, iron-rich core, the mantle made of silicate (硅酸盐) that are semi-molten at depth, and the thin, solid-surface crust There are two kinds of crust, a lower and denser oceanic crust and an upper，lighter continental crust found over only about 40 pe

2、rcent of the Earths surface. The rocks of the crust are of very different ages. Some continental rocks are over 3,000 million years old, while those of the ocean floor are less than 200 million years old. The crusts and the top, solid part of the mantle, totaling about 70 to 100 kilometers in thickn

3、ess, at present appear to consist of about 15 rigid plates, 7 of which are very large. These plates move over the semi-molten lower mantleto produce all of the major topographical(地形学的)features of the Earth. Active zones where intense deformation occur are confined to the narrow, interconnecting bou

4、ndaries of contact of the plates.There are three main types of zones of contact: spreading contacts where plates move apart, converging contacts where plates move towards each other, and transform contacts where plates slide past each other. Newoceanic crust is formed along one or more margins of ea

5、ch plate by material issuing from deeper layers of the Earth s crust, for example, by volcanic eruptions (爆发) of lava (火山熔岩) at mid-ocean ridges. If at such a spreading contact the two plates support continents，a rift(裂缝) is formed that will gradually widen and become flooded by the tea. The Atlanti

6、c Ocean formed like this as the American and Afro-European plates moved in opposite directions. When two plates carrying continents collide, the continental blocks,too light to be drawn down, continue to float and therefore buckle (起褶皱) to form a mountain chain along the length of the margin of the

7、plates.练习题：Choose correct answers to the question:1.The Earths crust_.A.can be classified into two typesB.is formed along the margins of the platesC.consists of semi-molten rocksD.is about 70 to 100 kilometers thick2.The 15 plates of the Earth are formed from _.A.the oceanic crusts and continental c

8、rustsB.the crusts and the mantleC.the crusts and the top and solid part of the mantleD.the continental crusts and the solid part of the mantle3.Seriously-deformed zones appear _A.whenever the crusts move over mantleB.when the plates move towards each otherC.in the narrow boundaries where two plates

9、meetD.to be the major topographical feature of the Earth4.According to the second paragraph, the formation of the Atlantic Ocean is the example of_.A.spreading contactsB.the influence of volcanic eruptionsC.converging contactsD.transform contacts5.This passage is probably_.A.a newspaper advertisemen

10、tB.a chapter of a novelC.an excerpt from a textbookD.a scientific report of new findings二A remarkable variety of insects live in this planet More species of insects exist than all other animal species together. Insects have survived on earth for more than 300 million years, and may possess the abili

11、ty to survive for millions more.Insects can be found almost everywhere - on the highest mountains and on the bottom of rushing streams, in the cold South Pole and in bubbling hot springs. They dig through the ground, jump and sing in the trees,and run and dance in the air. They come in many differen

12、t colors and various shapes. Insects are extremely useful to humans, pollinating (授粉)our crops as well as flowers in meadows, forests, deserts and other areas. But licks and some insects, such as mosquitoes and fleas, can transmit disease.There are many reasons why insects are so successful at survi

13、ving. Their amazing ability to adapt permits them to live in extreme ranges of temperatures and environments. The one place they have not yet been found to any major extent is in the open oceans. Insects can survive on a wide range, of natural and artificial foodspaint, pepper, glue, books, grain, c

14、otton，other insects, plants and animals Because they are small they can hide in tiny spaces.A strong, hard but flexible shell covers their soft organs and is resistant to chemicals, water and physical impact. Their wings give them the option of flying away from dangerous situations or toward food or

15、 males. Also, insects have an enormous reproductive capacity: An African ant queen can lay as many as 43,000 eggs a day.Another reason for their success is the strategy of protective color. An insect may be right before our eyes, but nearly invisible because it is cleverly disguised like a green lea

16、f, lump of brown soil, gray lichen (青苔),a seed or some other natural object Some insects use bright, bold colors to send warning signals that they taste bad,sting or are poison.Others have wing patterns that look like the eyes of a huge predator, bitter-tasting insects; hungry enemies are fooled into avoiding them.练习题：Choose cor