机电技术专业英语 教学课件 作者 徐起贺 张庆良pata a lesson one.pptVIP

* 机电技术专业英语 PART B Reading Materials Lesson One Text In industry today there are more than a thousand different metals being used to manufacture products. The modern automobile has more than one hundred different metals used in its construction. An attempt will be made in this passage to give an understanding of the basic classification of metals. Metals were formerly thought to be those elements that had a metallic luster and were good conductors of heat and electricity1. Actually, metals are generally defined as those elements whose hydroxides form bases (such as sodium or potassium). The nonmetals，hydroxides form acids (such as sulphur). Metals may exist as pure elements. When two or more metallic elements are combined, they form a mixture called an alloy. Classification of Metals Lesson One New Words and Expressions Lesson One Lesson One Notes 1. Metals were formerly thought to be those elements that had a metallic luster and were good conductors of heat and electricity. 金属过去被认为是具有金属光泽、良好的导热性和导电性的物质。 句中,metals为主语,that引导的定语从句修饰宾语elements。 2. In metallurgy it is a substance, with metallic properties, that is composed of two or more elements, intimately mixed. 在冶金学中，合金是由两种或两种以上的元素均匀混合，具有金属特性的物质。 句中的in metallurgy为状语, with metallic properties为插入语, 由that引导的定语从句修饰表语a substance。 3. The proportion of the alloying element that remains in solid solutions has a tendency to vary with the temperature and grain structure of the alloy that is formed. 固溶体里的合金元素的溶解率取决于温度以及合金形成的晶粒结构。 句中的主语较长，且有定语从句修饰，需要仔细斟酌。The proportion of the alloying element为主语，that remains in solid solutions为修饰主语的定语从句。to vary with the temperature and grain structure of the alloy that is formed是用来进一步解释tendency的。 Lesson One Lesson One 参考译文 在现代工业中，有近千种金属应用于生产。现代汽车的制造就需要用一百多种金属。下面，我们将试图通过这篇文章让大家对金属的基本分类有个了解。 过去，金属被认为是具有金属光泽及良好的导热性和导电性的物质。实际上，金属一般被定义为其氢氧化物为碱性的物质（如钠、钾），而非金属则被定义为其氢氧化物为酸性的物质（如硫磺）。金属可以是由单一元素构成的纯金属，也可以是由两种或两种以上金属元素组成的化合物，这种化合物就称为合金。 金属的分类 谢