Unit 11CAD and ApplicationsI. Lead inInformation related to the textDo you know what the Computer Aided Design (CAD) is? Do you know the history of CAD? What are the advantages of the CAD? Maybe you have used the CAD yet, but do you know how you can use it? Can you give an example? In the unit, you will study the development of CAD and how it is widely used. Now, let’s study new words and phrases together.II. Word Study1. appropriate [ə'prəuprieit] a. 适当的v. 占用；拨出1）Use the lists below to select the appropriate delimiter.请用下面的列表选择相应的定界符。
2）A focus and concern on climate change is entirely appropriate.对于气候变化的聚焦和关注是完全恰当的。
3）This is the "all appropriate measures" school of policy analysis.这是政策分析中的“所有适当措施”学派。
2. interactive [,intə'ræktiv] a. 交互式的，相互作用的1）Reading is a complex and interactive process.阅读是一个复杂和互动的过程。
2）A dialog between a user and an interactive data processing system.一种用户与交互式数据处理系统间的对话（过程）。
3）EVEN when one person is doing all the talking, a conversation is an interactive process. 即使只是一个人在滔滔不绝，谈话也是一项双边交流的过程。
3. standard ['stændəd] n. 标准，规格a. 标准的1）The standard answer is that we need better leaders.标准答案就是，我们需要更好的领导。
2）For such a series it is usual to design a standard margin .对于这种系列图幅，通常是设计一种标准图廓。
3）We see that this is the standard of perfection attained under nature.我们可以看到这就是自然界中所得到的完善化的标准。
4. sophisticate [sə'fistikeit] n. 久经世故的人v. 曲解；使复杂，使精致1）If you are wrong, admit it rather than sophisticate.错了就要承认，不要强词夺理。
2）Alter with the intention to deceive; Sophisticate rose water with geraniol.因试图欺骗而改变；用奉承话诡辩。
5. ambiguous [æm'bigjuəs] a. 模棱两可的，不明确的，含糊的1）He is so careful as not to say anything ambiguous.他总是小心谨慎，从不说任何引起歧义的话。
2）A sentence of a grammar is ambiguous if there exists two syntax trees for it.如果一文法的句子存在两个语法树，那么该句子是二义性的。
3）This ambiguous bit of jargon usually refers to situations, such as when interest rates fall to zero, where orthodox monetary policy can no longer affect demand.这个模糊不清的术语通常指的是这种情况，例如当利率降到零，传统的货币政策将不再能影响需求。
6. representation [,reprizen'tei ən] n. 表示法，表达，代表1）Our firm has adequate representation in Europe.本公司在欧洲有足够的代理权。
2）A representation in mathematical terms of a process , device, or concept.用数学上的术语对过程、器件或概念的一种表示。
3）Most of the definitions and concepts in graph theory are suggested by the graphical representation.图论中的大多数定义和概念是根据图形的表示提出来的。
III. Language points1. This coincidentally happened at about the same time that NC and APT (Automatically Programmed Tool) first appeared.译文：CAD与初次出现的NC和APT(自动编程工具)碰巧同时问世。
说明：coincidentally为副词作状语，at about the same time为介词短语，可译为“几乎同时”。
e.g.1) This category started at about the same time as Best Map Location.这个评选的开始时间大概和最佳地图场所差不多。
2) Not coincidentally, cities began to take shape at about the same time.城市也大约在同时开始现出雏形，而这并非巧合。
2. An interesting note is that an X-Y plotter has the same basic structure as an NC drilling machine except that a pen is substituted for the tool on NC spindle.译文：一个有趣的现象：除了绘图笔被NC机床上的主轴刀具替代之外，X-Y绘图仪与NC钻床具有相同的基本结构。
说明：“the same…as” means “similar”（与……相同），as为介词，引导短语。
e.g.1) Rural children face the same risks as city children.乡村孩子和城市孩子面临同样的危险。
2) Ancient mutations in mitochondrial DNA are the same as those found in the cells of many tumors.而在线粒体DNA中的远古突变和许多瘤细胞中发现的情况是一样的。
3. In the beginning, CAD systems were no more than a graphics editor with some built-in design symbols.译文：开始，CAD系统仅仅是一个带有内置设计符号的绘图编辑器。
说明：“no more than” means “only”(仅仅，只有),e.g.1) In the medium term there are only two ways to bring the deficit back toa sustainable level—which means no more than 3% of GDP.从中期来看，只有两种办法能够将赤字减低到可持续运行的水平，即赤字不能超过国内生产总值的3%。
2) Although many programmes are no more than three or four mouse clicks away, that still sounds too much like work for most of us.虽然很多节目只需点三四下鼠标就能轻而易举的获得，但那对大多数懒惰的我们来说也是项大工程。
4. The development of free-form curves and surfaces, such as Coon’s patch, Bezier’s patch, and B-spline, enables a CAD system to be used for sophisticated curves and surface design.译文：自由曲线及其曲面的发展，如昆氏嵌面、贝赛尔嵌面以及B样条曲线，使CAD系统可用于复杂曲线与曲面设计。
说明：“such as” means “like” or “for example”(例如，诸如此类的，像……那样)，e.g.1) And simple measures such as hand washing can limit the spread of disease.一些简单的措施，例如洗手可以有效的限制疾病的传播。
2) And simple measures such as hand washing can limit the spread of disease.一些简单的措施，例如洗手可以有效的限制疾病的传播。
5. Therefore, not only can they be used to produce engineering drawing, but engineering analysis can be performed on the same model as well.译文：因此，它们不仅可用于生成工程图，而且也可在同一模型上完成工程分析。