Seen from the space, the most striking feature of the earth is its sheer physical variety. Not only is there dry land and open s

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问题    Seen from the space, the most striking feature of the earth is its sheer physical variety. Not only is there dry land and open sea, but there are also mountains, plains, rivers, coastal shelves, and deep oceanic trenches. The earth also varies in its climate; in some parts of the world, weeks or months pass by under almost cloudless skies, while in other, the ground is scoured by icy winds or soaked by intense tropical storms. Differences like these create a complex jigsaw of varied habitats, enabling the earth to support a rich diversity of animal life. Some species are highly adaptable, and can survive in a wide range conditions, but the vast majority are found in one kind of habitat and nowhere else.
   In its narrowest sense, a habitat is the environment in which something lives. For some animals, a habitat might be as restricted as a temporary pool in a desert or as small as a piece of decaying wood. In a broader sense, a habitat can mean a characteristic grouping of living things, together with the setting in which they are found. In ecology, a habitat defined in this way is known as a biome.
   Habitats contain both living and non-living matter. In some—for example, true deserts—living things are thinly scattered, so the non-living part of the environment is dominant. In others, such as forest and coral reefs, living things are so abundant that they fill all the available space and create habitats for each other. In these habitats, huger numbers of species exist side by side, forming extraordinarily complex webs of life.
   Geology plays a part in shaping habitats, but by far the most important factor is climate. As a result, differences in climate—which sometimes occur over remarkably small distances—can have a huge effect on plants and animal life. A classic example of this occurs where mountain ranges intercept rain-bearing winds. On the windward side of the mountains, heavy rainfall often creates lush forests teeming with all kinds of animal life. But in the "rainshadow" , to the lee of the mountains, low rainfall can produce desert or scrub, where only drought-tolerant animals can survive.
   Temperature is another climatic factor that has an important effect both on land and in the sea. For example , in the far north, coniferous forest eventually peters out in the face of biting winter frosts. This northern tree-line, which runs like a ragged ring around the Arctic, marks the outer range of crossbills, wood wasps, and many other animals that depend on conifers for survival. On coasts and at sea, temperature changes are u-sually more gradual than they are inland. However, warmth—or lack of it-—still determines where some habitats are found. For example, reef-building corals do not thrive at temperatures of less than about 20 degrees, so most reefs are found in the tropics. However, on the west coast of Africa and the Americas, reefs are rare because, although the climate is warm, cold currents pass close to the shore. Mangrove swamps present a similar pattern: in the southern hemisphere, they reach as far as South Australia; in the northern hemisphere, they extend only just out of the tropics.
The word "ragged" in Paragraph 5 can be replaced by______.

选项 A、oval
B、broken
C、irregular
D、cold

答案C

解析 词义理解题。ragged一词位于第五段第三句,是用来修饰ring的。再结合这个圆环是围绕着北极的,可知,北极的边缘是参差不齐的。故ragged意为“参差不齐”。选项中,只有[C]项符合,故为答案。
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