英语翻译2.Either a shaft-based system or a hole-based system may

英语翻译
2.Either a shaft-based system or a hole-based system may be used .For any given basic size ,a range of tolerances and deviations may be specified with respect to the line of zero deviations ,called the zero line .The tolerance is a function of he basic size and an is designated by a number symbol ,called the grade―thus the tolerance grade .The position of the tolerance with respect to the zero line also a function of the basic size--is indicated by a letter symbol (or two letters ) ,a capital letter for holes and a lowercase letters for shafts .The specification forget a hole and shaft having a basic size of 45 mm might be 45 H8/g7 .
3.CAD system can created and displayed graphic information on a cathode-ray tube (CRT ),and it allows the designer to produce finished engineering drawings from single pensile sketches or from models and modify these drawings on the screen if they do not seem functional .From three-drawing ,orthographic views ,the designer can transform drawings into athree-dimensional views .This enable a designer to redesign a part on the screen ,project how the part will operate in use ,and make successive design changes in a matter of minutes .

要么一轴为基础的系统或一个洞为基础的系统也可使用.对于任何给定的基本尺寸,公差和偏差的范围可以指定相对于零偏差线,称为零线.该宽容是他的基本功能和大小是由指定的一个数字符号,被称为二级从而公差等级.作者：相对于零线也是基本尺寸公差的功能定位 - 是表示,由一个字母符号（或两个字母）,一孔,轴用小写字母大写字母.该规范忘记了一个洞,竖井有一个基本的45毫米大小可能是45 H8/g7
CAD系统可以创建并显示在阴极射线管（CRT）的图形信息,并且它允许设计人员从单一的生产悬挂草图或模型,完成了从工程设计图纸和修改这些图纸在屏幕上,如果他们似乎并不实用.从三冲,三视图,设计人员可以转化为athree二维图纸的意见.这使设计师能够在屏幕上重新设计,项目将如何运作的一部分使用,并在几分钟之内相继设计变化的一部分.