第 12、13、15、20、22课的翻译暂时没有。翻译标准。请放心使用。翻译整理于网络， 第一课Text:It is known that metals are very important in our life. Metals have the greatest importance for industry. Allmachines and other engineering7endVi5niEriN constructions have metal5metl parts; some of them consistonly of metal parts.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 elements5elimEnt2) Alloys5AlCi- 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 metalis iron5aiEn, which in the form of alloys with carbon5kB:bEn and other elements, finds greater use than anyother metal. Metals consisting of iron combined with some other elements are known as ferrous5ferEs metals;all the other metals are called nonferrous5nCn5ferEs metals. The most important nonferrous metal arecopper5kCpE, aluminumE5lju:minEm, leadli:d, zincziNk, tintin, but all these metals are used muchless 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 properties5prCpEti of alloysare much better than the properties of purepjuE metals. Only aluminum may be largely used in the form ofsimple metal. Metals have such a great importance because of their useful properties or their strength, hardness,and their plasticityplAs5tisiti.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。Different metals are produced in different ways, but almost all the metal are found in the forms of metaloreC:(r) (iron ore, copper ore, etcet cetra.)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 mineral5minErEl consistence of a metal combined with some impuritiesim5pjuEriti. Inorder to produce a metal from some metal ore, we must separate these impurities from the metal that is doneby metallurgyme5tAlEdVi.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 MaterialsText:Plastics5plAstik, plB:stik have specific properties which may make them preferable5prefErEbl totraditional materialsmE5tIErIEl for certain uses. In comparisonkEm5pArisn with metals, for example,plasticshavebothadvantagesanddisadvantages.MetalstendtobecorrodedkE5rEudbyinorganic7inC:5Anik acids5AsId, such as sulphuricsQl5fjuErik acid and hydrochloric7haidrEu5klC:rikacid. Plastics tend to be resistant to these acids, but can have dissolved or deformed by solvent5sClvEnt, suchas carbon tetrachloride7tetrE5klC:raid, which have the same carbon base as the plastics. Color must beapplied to the surface of metals, whereas it can be mixed in with plastics. Metals are more rigid5ridVid thanmost plastics while plastics are very light, with a specificspi5sifik gravity normally between 0.9 and 1.8.Most plastics do not readily5redili conduct5kCndQkt heat or electricityIlek5trIsItI. Plastics soften slowlyand can easily be shapedFeip 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。It is their plasticityplAs5tisiti at certain temperatures5temprItFE(r) which gives plastics their mainadvantages over many other materials. It permits the large-scale production of moldedmEuld articles, suchas containers, at an economic unit cost, where other materials require laboriouslE5bC:riEs and often costlyprocesses involving cutting, shaping, machining, assemblyE5sembli and decoration.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 exploitediks5plCit for entirelyIn5taIElInew applications. For example, plastics heart valvesvAlv and other human spare parts have make possiblemany recent developments in surgery5sE:dVEri.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 mostsuitable plastics should be chosen, and if neces