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VI. Read the following summary of the previous text and fill in the miss­ing information with the words given.

Automation of machine tools began in the 20th century. In the 1950s the first machines with … were … .

Numerical… is a system of automating machine … .

Computer … control machine tool is directed by a … . CNC machines are easy in … and they are … to maintain.

In … system a single computer may … more than 100 machine tools.

Machining centres may … a lot of machining … on a … at a time. One machining centre may do the work of eight… machines.

… NC systems have … advantages.

computer

in general

introduced

tools

perform

a lot of

numerical control

operation

numerical

operations

control

direct numerical control

standard

cheaper

workpiece

VII. Annotate the text.

18.

Copper

Modal Verbs

Copper Application in Engineering

Lead-in

I. Discuss the following questions.

a) How much do you know about copper?

b) Where is copper used today? Make a list of possible applications of copper. Compare it with that of your groupmates.

c) Do you know any copper alloys? What are their constituents?

II. The students are at the seminar on metals technology. Listen to their discussion and learn what properties copper has and where it can be used.

Teacher: Dear students, today we're going to discuss the main pro­perties and applications of copper. So far, what can you say about this metal?

Andrew: If I'm not mistaken, copper is a non-ferrous metal. And it can be found in a free state in nature.

Alice: And as far as I remember, people were able to extract this metal in prehistoric times. Various things such as weapons, tools and decorations could be made of it.

Teacher: Very good. Were those copper tools very reliable? ,

Andrew: I think not. Pure copper is a soft ductile metal. Strong cutting tools could be made only of copper alloys such as bronze.

Teacher: OK. What are the present applications of copper?

Alice: Well, they are numerous. Copper metals can be used in most domestic appliances. Electrical industry is impossible without copper wiring as it is a very good conductor of electricity. Also, copper is corrosion resistant which makes it valuable for marine industry. Besides, this metal is even used in making money!

Teacher: You are quite right. Tomorrow we will be able to study the valuable properties of copper in-the practical class.

III. Complete the dialogue.

A: – Are we going ….today?

B: – … . Let's remember what…

A: – I know that copper ….

B: Very well, and when ….?

A: – …

B: – What applications ….?

A: –

B: – Why did bronze become so …?

A: –

B: – Can you prove that copper … today?

A: –

B: – What valuable properties … ?

A: – Well, …

B: – Excellent! I see you know a lot about copper.

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