问题 问答题

数控机床有哪几种分类方法

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参考答案:

解析:数控机床有以下几种分类方法: 按照刀具与工件的相对运动轨迹可将数控机床分为点位控制数控机床和轮廓控制数控机床。 按照伺服系统的控制方式可将数控机床分为闭环控制数控机床、半闭环控制数控机床和开环控制数控机床。 按照加工方式可将数控机床分为金属切削类数控机床、金属成型类数控机床、特种加工类数控机床和其他类数控机床。 按照CNC装置的功能水平可将数控机床分为高、中、低档三类数控机床。

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阅读下面短文,根据所读内容在文章后表格中的空格里填入一个最恰当的单词。

注意:表格中的每个空格只填一个单词。请将答案写在答题卡相应题号的横线上。

Everyone knows that you can study the English language for years and still not understand a

native speaker of English when you meet one. Everyone knows that native speakers say a lot of

things that you can't find in any dictionary. Well, here's a secret for you: a lot of British people

can't understand each other either!

There are different local accents across the UK, and a number of areas have several different dialects, that is, they have their own unique vocabulary and grammatical phrases. There were at least six different accents born to London the last time I counted.

Worse than that, it is not just where a person is born in the UK that decides their accent. For example, a language and its accents often vary across class or level of education. Another example is how language can differ among age groups in the UK. The words and pronunciation used by young people in the UK can be completely different compared with those used by adults. They are

creating a "yoof culture".

The word "yoof'”is an informal spelling of "youth". Some people don't consider "yoof' to be a positive term, since its pronunciation is easier and lazier than "youth". Other people see the term

as positive, because it describes how young people are creating their own language, concepts and

identity. When parents find it difficult to understand their children, the children can say more things without the examining of their parents. In this way, young people are starting to find freedom, independence and self-expression. Even though certain groups of society feel threatened

by "yoof culture", new words come and go like fashions.

Therefore, learners should not worry about communicating with native speakers so much. Even British people don't speak English properly! The UK no longer owns the English language.