众所周知，金属在我们的生活中是非常重要的，金属对于工业而言是有巨大的重要性，所有机器和 其他工程构造都有金属零部件，其中一些还只能由金属组成。
There are two large groups of metals: 1) Simple metal- more or less pure chemical elements[5elimEnt] 2) Alloys[5AlCi]- materials consisting of a simple metal combined with some other elements. 有两大类金属：（1）纯金属——或多或少的金属元素（2）合金——组成纯金属的原料结合其他元 素。 About two thirds of all elements found in the earth are metals, but not all metals may be used in industry. Those metals which are used in industry are called engineering metals. The most important engineering metal is iron[5aiEn], which in the form of alloys with carbon[5kB:bEn] and other elements, finds greater use than any other metal. Metals consisting of iron combined with some other elements are known as ferrous[5ferEs] metals; all the other metals are called nonferrous[5nCn5ferEs] metals. The most important nonferrous metal are copper[5kCpE], aluminum[E5lju:minEm], lead[li:d], zinc[ziNk], tin[tin], but all these metals are used much less than ferrous metals, because the ferrous metals are much cheaper. 在地球上发现的所有元素中，大约三分之二是金属元素，但是并不是所有的金属都能够用于工业上。 那些金属—我们用于工业上的金属—被称为工程金属，最重要的工程金属那就是铁，铁跟碳和其他元素 结合形成合金的那些金属比其他金属发现有更大用途。铁与别的其他某些元素相结合而组成的金属称为 黑色金属，此外所有其他金属都称为有色金属，最重要的有色金属是---铜，铝、铅、锌、锡。但是使 用这些有色金属比使用黑色金属要少的多，因为黑色金属便宜得多。 Engineering metals are used in industry in the form of alloys because the properties[5prCpEti] of alloys are much better than the properties of pure[pjuE] metals. Only aluminum may be largely used in the form of simple metal. Metals have such a great importance because of their useful properties or their strength, hardness, and their plasticity[plAs5tisiti]. 因为合金的特性比纯金属的好，所以工程金属以合金的形式用于工业，只有铝以纯金属的形式被广 泛应用。金属因为具有强度、硬度和可塑性而发挥着特别重要的作用。
塑料不仅可以代替其他材料，而且它的特性能被开拓应用于全新领域，比如：随着最近外科手术的 发展可能做成塑料的心脏瓣膜和其他人类的器官。
There is no single plastics material which is suitable for all applications. It is important that the most suitable plastics should be chosen, and if necessary adapted[E5dApt], for each particular requirement. It is also important that the properties of the plastics chosen should be exploited to the best advantage.
矿石是一种由金属与某些杂质相混合而组成的矿物质，为了用金属矿石来生产出一种金属，我们必 须把杂质从金属矿中分离出去，那就要靠冶炼来实现。
2. Plastics and Other Materials
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Plastics[5plAstik, plB:stik] have specific properties which may make them preferable[5prefErEbl] to traditional materials[mE5tIErIEl] for certain uses. In comparison[kEm5pArisn] with metals, for example, plastics have both advantages and disadvantages. Metals tend to be corroded[kE5rEud] by inorganic[7inC:5^Anik] acids[5AsId], such as sulphuric[sQl5fjuErik] acid and hydrochloric[7haidrEu5klC:rik] acid. Plastics tend to be resistant to these acids, but can have dissolved or deformed by solvent[5sClvEnt], such as carbon tetrachloride[7tetrE5klC:raid], which have the same carbon base as the plastics. Color must be applied to the surface of metals, whereas it can be mixed in with plastics. Metals are more rigid[5ridVid] than most plastics while plastics are very light, with a specific[spi5sifik] gravity normally between 0.9 and 1.8. Most plastics do not readily[5redili] conduct[5kCndQkt] heat or electricity[Ilek5trIsItI]. Plastics soften slowly and can easily be shaped[Feip] when they are soft.
塑料具有特殊的性能。对于某种用途而言，这些性能使得塑料比传统材料更为可取。例如，跟金属 相比较，塑料既有优点也有缺点。金属易受到无机酸的腐蚀，如硫酸和盐酸，塑料能抵抗这些酸的腐蚀， 但可被溶剂所洛解或引起变形，例如溶剂四氯化碳与塑料具有同样的碳基。颜色必定只能涂到金属的表 面。而它可以跟塑料混合为一体。金属比大多数塑料刚性要好，而塑料则非常之轻，通常塑料密度在 0. 9-1. 8 之间。大多数塑料不易传热导电。塑料能缓慢软化，而当其还是在软的状态时，能容易成形。
该翻译整理于网络， 但并不是用什么软件翻译 的，而是一些专业老师翻 译的，其中就包括我们学 校交专业英语的老师。
第 12、13、15、20、 22 课的翻译暂时没有。
翻译标准。请放心使 用。
第一课
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It is known that metals are very important in our life. Metals have the greatest importance for industry. All machines and other engineering[7endVi5niEriN] constructions have metal[5metl] parts; some of them consist only of metal parts.
没有一种纯塑料材料适用于各个领域，如果有必要改进，对于每个有特殊要求的来说选择最合适的 塑料是最重要的，被选择的塑料材料的特性被开拓得到更好的应用也是很重要的。
在某一温度下塑料是处于塑性状态的，这就使塑料具备超过许多其他材料的主要优点。它容许大量 生产单位成本低廉的模制式器件，例如，各种容器。于此，若用其他材料则需要大量劳力和往往需要很 费钱的加工工艺，比如，切割、成形、加工、装配和装饰。
Plastics not only replace other materials. Their properties can be exploited[iks5plCit] for entirely[In5taIElI] new applications. For example, plastics heart valves[vAlv] and other human 'spare parts' have make possible many recent developments in surgery[5sE:dVEri].
以不同的方法生产不同的合金但是几乎所有的金属都是以金属矿的形式（铁矿、铜矿）被发现的。 The ore is a mineral[5minErEl] consistence of a metal combined with some impurities[im5pห้องสมุดไป่ตู้uEriti]. In order to produce a metal from some metal ore, we must separate these impurities from the metal that is done by metallurgy[me5tAlEdVi].