[外语类试卷]大学英语六级模拟试卷171及答案与解析.doc
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1、大学英语六级模拟试卷 171及答案与解析 一、 Part I Writing (30 minutes) 1 Directions: For this part, you are allowed 30 minutes to write a composition on the topic Wealth and Health. You should write at least 150 words and you should base your composition on the outline (given in Chinese) below. 1. 有人认为财富比健康重要 : 2也有人认为
2、健康比财富重要; 3我的观点是 _。 二、 Part II Reading Comprehension (Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For questions 1-4, mark: Y (for YES) if the statement agrees with the informati
3、on given in the passage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions on Answer Sheet 1. Fo
4、r questions 1-4, mark Y (for YES) if the statement agrees with the information given in the passage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. For questions 5-10, complete the sentences with the in
5、formation given in the passage. Earths Beginnings: The Origins of Life Earth is the only planet we know of that can support life. This is an amazing fact considering that it is made out of the same matter as other planets in our solar system, was formed at the same time and through the same processe
6、s as every other planet, and gets its energy from the sun. To a universal traveler, Earth may seem to be a harmless little planet in the far reaches of one of billions of spiral galaxies in the universe. It has an average size star of average brightness and is joined by eight other planetswhich supp
7、ort no known life formsin its solar system. However, Earth is a planet teeming with vitality and is home to billions of plants and animals that share a common evolutionary track. How and why did we get here? What processes had to take place for this to happen? And where do we go from here? The fact
8、is, no one has been able to come close to knowing exactly what led to the origins of life, and we may never know. After 4.5 billion years of Earths formation and evolution, the evidence may have been lost. But scientists have made significant progress in understanding what chemical processes that ma
9、y have led to the origins of life. There are many theories, but most have the same general perspective of how things came to be the way they are. Following is an account of lifes beginnings based on some of the leading research and theories related to the subject, and of course, fossil records datin
10、g back as far as 3.5 billion years ago. Earths Beginnings Earth began to form over 4.5 billion years ago from the same cloud of gas (mostly hydrogen and helium) and interstellar dust that formed our sun, the rest of the solar system and even our galaxy. In fact, Earth is still forming and cooling fr
11、om the galactic implosion that created the other stars and planetary systems in our galaxy, a process which began about 16 billion years ago as the Milky Way began to form. As our solar system began to come together some 67 billion years ago, the sun formed within a cloud of dust and gas that contin
12、ued to shrink upon itself by its own gravitational forces. This caused it to undergo the fusion process and give off light, heat and other radiation. During this process, the remaining clouds of gas and dust that surrounded the sun began to form into smaller lumps called planetesimals, which eventua
13、lly formed into the planets we know today. The Earth went through a period of catastrophic and intense formation during its earliest beginnings about 4.54.6 billion years ago. By 3.8 to 4.1 billion years ago, Earth had become a planet with an atmosphere (not like our atmosphere today!) and an ocean.
14、 This period of time of Earths formation is referred to as the pre-Cambrian Period. The pre-Cambrian is divided into three parts: the Hadean, Archean and Proterozoic Periods. Pre-Cambrian Period The Earth formed under so much heat and pressure that it formed as a molten planet. For nearly the first
15、billion years of its formationcalled the Hadean Period (or “hellish“ period)Earth was bombarded continuously by the remnants of the dust and debrislike asteroids, meteors and cometsuntil it formed into a solid sphere, fell into an orbit around the sun, and began to cool down. As Earth began to take
16、solid form, it had no free oxygen in its atmosphere. It was so hot that the water droplets in its atmosphere could not settle to form surface water or ice. Its atmosphere was also so poisonous that nothing would have been able to survive. Earths atmosphere was formed mostly from the outgassing of su
17、ch volatile compounds as water vapor, carbon monoxide, methane, ammonia, nitrogen, carbon dioxide, hydrochloric acid and sulfur produced by the constant volcanic eruptions that besieged the Earth. It had no flee oxygen. About 4.1 billion years ago, the Earths surfaceor crustbegan to cool and stabili
18、ze, creating the solid surface with its rocky terrain. Clouds formed as the Earth began to cool, producing enormous volumes of rain water that formed the oceans. For the next 1.3 billion years (3.8 to 2.5 billion years ago), called the Archean Period, first life began to appear (at least as far as o
19、ur fossil records tell us. there may have been life before this!) and the worlds land masses began to form. Earths initial life forms were bacteria which could survive in the highly toxic atmosphere that existed during this time. In fact, all life was bacteria during the Archean Period. Toward the e
20、nd of the Archean Period and at the beginning of the Proterozoic Period, about 2.5 billion years ago, oxygen-forming photosynthesis began to occur. The first fossils, in fact, were a type of blue-green algae that could photosynthesize. Some of the most exciting events in Earths history and life occu
21、rred during this time which spanned about two billion years until about 550 million years ago. The continents began to form and stabilize, creating the supercontinent Rodinia about 1.1 billion years ago. (Rodinia is widely accepted as the first supercontinent, but there were probably others before i
22、t.) Although Rodinia is composed of some of the same land fragments as the more popular supercontinent, Pangea, they are two different supercontinents. Pangea formed some 225 million years ago and would evolve into the seven continents we know today. Free oxygen began to build up around the middle o
23、f the Proterozoic Periodaround 1.8 billion years agoand made way for the emergence of life as we know it today. This event, of course, created conditions that would not allow most of the existing life to survive and thus made way for the more oxygen dependent life forms. By the end of the Proterozoi
24、c Period, Earth was well along in its evolutionary processes leading to our current period, the Holocene Period, also known as the Age of Man. Thus, about 550 million years ago, the Cambrian Period began. During this period, life “exploded,“ developing almost all of the major groups of plants and an
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