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求助新GRE阅读Excercise16的一道题 已有2人参与
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When a molten metal or metallic alloy is cooled to a solid, a crystalline structure is formed that depends on the particular alloy composition. In contrast, molten Line nonmetallic glass-forming materials, when cooled, do not 5 assume a crystalline structure, but instead retain a structure somewhat like that of the liquid--an amorphous structure. At room temperature, the natural long-term tendency for both types of materials is to assume the crystalline structure. The difference between the two is in 10 the kinetics or rate of formation of the crystalline structure, which is controlled by factors such as the nature of the chemical bonding and the ease with which atoms move relative to each other. Thus, in metals, the kinetics favors rapid formation of a crystal line structure, whereas 15 in nonmetallic glasses the rate of formation is so slow that almost any cooling rate is sufficient to result in an amorphous structure. 11. The author implies that the rate at which the molten materials discussed in the passage are cooled is a determinant of the (A) chemical composition of the resulting solids (B) strength of the chemical bonds that are formed (C) kinetics of the materials' crystalline structure (D) structure the materials assume (E) stability of the materials' crystalline structure 12. It can be inferred from the passage that, theoretically, molten nonmetallic glasses assume a crystalline structure rather than an amorphous structure only if they are cooled (A) very evenly, regardless of the rate (B) rapidly, followed by gentle heating (C) extremely slowly (D) to room temperature (E) to extremely low temperatures 第11题，文章第一句话不是说depends on the particular alloy composition，为什么不是A，要选E 第12题，文章只是说金属生成晶体速率要快，但非金属在任何较慢的速率都能生成非晶体，可是题目问的是非金属在什么条件下能产生晶体，请问这能推出来吗？ |
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6楼2014-07-16 22:01:58
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5楼2014-07-16 21:44:00
readbycandle
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