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发布时间：2006-06-21 20:59     点击：

(C) principle

(D) temperature

9. The word "Since" in line 20 is closest in meaning to

(A) later

(B) because

(C) during

(D) although

10. Which of the following is true of both the phlogiston theory of burning and Lavoisier's theory of burning?

(A) Both theories propose that total weight always increases during burning.

(B) Both theories are considered to be reasonable and straightforward.

(C) Both theories have difficulty explaining why residue remains after burning.

(D)Both theories recognize that air is important to combustion.

Questions 11-22

Iron production was revolutionized in the early eighteenth century when coke was first used instead of charcoal for refining iron ore. Previously the poor quality of the iron had restricted its use in architecture to items such as chains and tie bars for supporting arches, vaults, and walls. With the improvement in refining ore, it was now possible to make cast-iron beams, columns, and girders. During the nineteenth century further advances were made, notably Bessemer's process for converting iron into steel, Which made the material more commercially viable.

Iron was rapidly adopted for the construction of bridges, because its strength was far greater than that of stone or timber, but its use in the architecture of buildings developed more slowly. By 1800 a complete internal iron skeleton for buildings had been developed in industrial architecture replacing traditional timber beams, but it generally remained concealed. Apart from its low cost, the appeal of iron as a building material lay in its strength, its resistance to fire, and its potential to span vast areas. As a result, iron became increasingly popular as a structural material for more traditional styles of architecture during the nineteenth century, but it was invariably concealed.

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