托福阅读真题+题目+答案：Early Iron Metallurgy

托福阅读真题+题目+答案：Early Iron Metallurgy

Metallurgy-the science of working with metals such as iron in order to give them certain desired properties-has a long history. The first known objects made from metals date to the ninth millennium B.C.E. Usable iron is usually obtained from iron ore(raw iron)by smelting, a process by which iron is separated(reduced)from its ore by heating. Iron-ore smelting requires very high temperatures and good control of the temperature and reduction conditions. Achieving these was beyond the capabilities of the early metallurgists. Thus, the development of the earliest metallurgy concerned only other metals-gold, silver, copper, lead, and tin-around which a range of sophisticated technologies developed, practiced by experts and often managed by elites. The rarity of tin required for making bronze, played a key part in determining the pattern of trade routes, and the consequent expense restricted bronze use to important members of society.

1.According to paragraph 1, early metallurgists did not produce iron objects because

A.iron ores had not yet been discovered

B.iron smelting had a very high cost

C.they lacked the technology to smelt iron

D.other metals were available in large quantities

2.Paragraph 1 suggests that the earliest metallurgy techniques were developed around only gold, silver, copper, lead, and tin because

A.metallurgists could combine those metals to make valuable products

B.metallurgists could earn more because of the expertise required to work with those metals

C.those metals could be easily acquired through trade routes

D.those metals melt at relatively lower temperatures than iron

In about 1200 BCE, however, iron smelting began in western Asia. Iron ore needed to be reduced in a furnace at a high enough temperature to ensure that the slag(the material from which the iron has been separated) melted and ran off, leaving the iron “bloom”. A blown-air supply, provided by a device called a bellows, enabled the fuel to burn. The resulting bloom was a mass of metallic iron still containing impurities from the fuel, which had to be driven out by forging(heating and hammering), leaving wrought iron, a soft inferior metal that could not be hardened by heating. ▋Carburization, however, transformed wrought iron into useful low-carbon steel by incorporating 0.5 to 1.5 percent carbon, generally by using charcoal as the smelting fuel.▋Low-carbon steel was harder and stronger than bronze, and could take and keep an edge better; and its hardness could be varied by heating and cooling it. ▋Skilled and nuanced ironworking developed thereafter-expert smiths in western Europe, for example, produced swords with razor-sharp edges, hard, but easily broken, on softer, more elastic blades.▋

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