二、Translate the following sentences into Chinese....
二、Translate the following sentences into Chinese. (翻译每段30分,共90分) 1. Materials have always been important to the advance of civilization: entire eras are named for them. After evolving from the Stone Age through the Bronze and Iron Ages, now in the modem era we have vast numbers of tailored materials to make use of. We are really living in the Materials Age. Today we demand more from our materials than mechanical strength. The structure of a material usually relates to the arrangement of its internal components. Subatomic structure involves electrons within the individual atoms and interactions with their nuclei. 2. Die casting is the infant of modern metal casting methods. Its use is largely limited to the non-ferrous metals. The rapid chilling of the metal by its injection into bare steel molds provides for rapid production cycling but at the same time presents severe challenges to orderly mold filling. The first metals used for die casting were tin and lead, but their cost and limited mechanical properties limited their application. With the development of zinc base alloys before the first world war, the significance of tin and lead declined. Aluminum alloys were first used for commercial die casting. 3. Annealing has a second advantage, it helps to relieve any internal stresses which exist in the metal. These stresses are liable to occur through hammering or working the metal, or through rapid cooling. Metal which we cause to cool rapidly contracts more rapidly on the outside than on the inside. This produces unequal contractions, which may give rise to distortion or cracking. Metal which cools slowly is less liable to have these internal stresses than metal which cools quickly. On the other hand, we can make steel harder by rapid cooling.