文勇的新托福黄金&ccedil

Experiments to smile for example leads them

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Unformatted text preview: ○They occur less frequently now than they once did. ○They occur quickly in geological terms. 2. The word elatively in the passage is closest in meaning to r ○Unusually ○Comparatively ○Occasionally ○Naturally Paragraph 2: Hills and mountains are often regarded as the epitome of permanence, successfully resisting the destructive forces of nature, but in fact they tend to be relatively short­lived in geological terms. As a general rule, the higher a mountain is, the more recently it was formed; for example, the high mountains of the Himalayas are only about 50 million years old. Lower mountains tend to be older, and are often the eroded relics of much higher mountain chains. About 400 million years ago, when the present­day continents of North America and Europe were joined, the Caledonian mountain chain was the same size as the modern Himalayas. Today, however, the relics of the Caledonian orogeny (mountain­building period) exist as the comparatively low mountains of Greenland, the northern Appalachians in the United States, the Scottish Highlands, and the Norwegian coastal plateau. 3. Which of the following can be inferred from paragraph 2 about the mountains of the Himalayas? ○Their current height is not an indication of their age. ○At present, they are much higher than the mountains of the Caledonian range. ○They were a uniform height about 400 million years ago. ○They are not as high as the Caledonian mountains were 400 million years ago. 4. The word relics in the passage IS closest in meaning to ○Resemblances ○Regions ○Remains ○Restorations Paragraph 3: The Earth's crust is thought to be divided into huge, movable segments, called plates, which float on a soft plastic layer of rock. Some mountains were formed as a result of these plates crashing into each other and forcing up the rock at the plate margins. In this process, sedimentary rocks that originally formed on the seabed may be folded upwards to altitudes of more than 26,000 feet. Other mountains may be raised by earthquakes, which fracture the Earth's crust and can displace enough rock to produce block mountains. A third type of mountain may be formed as a result of volcanic activity which occurs in regions of active fold mountain belts, such as in the Cascade 83 Mail@liuwenyong.com 在在在在在在 www.liuwenyong.com 在在在在在在在在在在在在在在在,在在在在在在在在在在 Range of western North America. The Cascades are made up of lavas and volcanic materials. Many of the peaks are extinct volcanoes. 5. According to paragraph 3, one cause of mountain formation is the ○effect of climatic change on sea level ○slowing down of volcanic activity ○force of Earth's crustal plates hitting each other ○replacement of sedimentary rock with volcanic rock Paragraph 5: The weather, in its many forms, is the main agent of erosion. Rain washes away loose soil and penetrates cracks in the rocks. Carbon dioxide in the air reacts with the rainwater, forming a weak acid (carbonic acid) that may chemically attack the rocks. The rain seeps underground and the water may reappear later as springs. These springs are the sources of streams and r...
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