1. The builders will be shown some models of new bridges.
a)
b) .
c) .
2. The design of the dam was worked at by some institutes.
a) .
b) .
c) .
3. Complex calculations were followed by experiments
a) .
b) .
c) .
IV. . to be: ) ; ) -; ) ; ) . .
1. The worlds first radio receiver was built by Popov.
2. The spacing between repeaters is to be maximized.
3. Television is rapidly developing into one of the most popular means of conveying information.
4. An electric circuit is a path along which an electric current flows.
5. Many scientific centers are in the East of our country.
V. . to have: ) ; ) ; ) . .
1. To design electronic computer a we had to pass from radio valves to transistors.
2. All these systems have electronic components.
3. We have tried different approaches to overcome these difficulties.
VI. , .
1. You () to replace this old lathe.
2. In future we () to use solar energy more effectively.
3. They ( ) to test the machine-tool.
4. The students () to make the experiment.
a) were allowed; b) shall be able; c) have; d) were able; e) were
VII. .
1. They are allowed to replace the old equipment.
2. They have to replace the old equipment.
3. They were able to replace the old equipment.
a) must; b) could; c) may; d) might
VIII. .
Central processing unit
1. The central processing unit (CPU) or central processor is the nerve centre of any digital computer system, since it coordinates and controls the activities of all the other units and performs all the arithmetic and logic processes to be-applied to data. All program instructions to be executed must be held within the CPU, and all the data to be processed must be loaded first into this unit. It is convenient to consider the central processor to have three separate hardware sections: an internal or main memory, an arithmetic and logic unit, and a control unit. The role of the internal memory was discussed more detailed in the previous lesson. Now let us discuss the latter two sections
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2. The CPU has two functions: it must (1) obtain instructions from the memory and interpret them, as well as (2) perform the actual operations. The first function is executed by the control unit. This unit in its turn must perform two functions: it must (1) interpret the instruction; then, on the end of this interpretation (2) tell the arithmetic and logic what to do next. The latter function is accomplished through the use of electronic signals. According to these functions we can separate the part of the control unit that interprets or decodes the instruction called the instruction decoder from the part that generates the control signals called the control generator.
3. The second function of the CPU is performed by the arithmetic and logic unit which does the actual operations. This unit is capable of performing automatically addition, subtraction, multiplication, division, comparing, selecting and other mathematical and logical operations.
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I. :
- -:
1. This material is unaffected by solar radiation.
2. Some of these living things were tested by experiment.
3. Recently this model has been modified and now is being used in many practical situations.
4. The distribution of plants is greatly affected by local conditions.
5. The seminar will be attended by many participants.
6. His lectures were always followed by heated discussions.
