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7.Complete the second sentence so that it has a similar meaning to the first sentence, using the words given
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7. Complete the second sentence so that it has a similar meaning to the first sentence, using the words given
1. Starting a diesel engine is a harder task than starting a gasoline engine.
that of
2. The power produced in an economical 2 stroke engine is about 1. 5 times than the power of an economical 4 stroke engine.
that of
3. Diesel fuel evaporates (испаряется) much more slowly than gasoline: its boiling point is actually higher than the boiling point of water.
that of
4. Advantages of the four-stroke cycle over advantages of two-stroke cycle are the fuel efficiency and cleanliness.
those of
5. Weight, noise and efficiency of diesel engines are more than weight, noise and efficiency of gasoline engines.
those of
8. Read the text, divide it into paragraphs and give a heading to each paragraph. Which of the linking words in bold help you understand that the author a) adds some new information? b) explains the reason? c) expresses contrast; d) shows the effect
The Two-Stroke Cycle
The two-stroke engine is simpler mechanically than the four-stroke engine. The two-stroke engine delivers one power stroke every two strokes instead of one every four, thus it develops more power with the same displacement, or can be lighter and yet deliver the same power. For this reason, it is used in lawn mowers, chain saws, small automobiles and motorcycles. However, there are several disadvantages that restrict its use. Since there are twice as many power strokes during the operation of a two-stroke engine as there are during the operation of a four-stroke engine, the engine tends to heat up more, and thus is likely to have a shorter life. Also, in the two-stroke engine lubricating oil must be mixed with the fuel. This causes a very high level of hydrocarbons in its exhaust, unless the fuel-air mixture is computer calculated in order to maximize combustion.
9. Read the text and think of the word which best fits each space
Diesel engines, like gasoline-burning ones, are internal 1___________ engines. That means that fuel is 2___________ with air as it goes into the engine and that 3___________ is compressed internally, inside the engine’s cylinders. At some point, the fuel 4_________ driving a piston down and turning the crankshaft, which is connected to the vehicle’s transmission and turns the wheels. The piston then moves up in the 5_________, pushing the burnt gases out of the engine. This cycle repeats several times per second.
10. Read the text choosing the correct alternative in brackets
The main (differ/difference/different) between diesel and gas engines is in the way how the fuel is (ignite/ignited/ignites) inside the engine. In a gas engine, the air and fuel are (compressed/compress/compression) and, at a critical point in the timing of the cycle, a spark plug ignites the (mixing/mixture/mix). But in a diesel engine, there (/is/were/are) no spark plugs. When diesel fuel and air are squeezed enough, the extreme compression generates ( heat/heated/heats) that the mixture spontaneously combusts. This is (known/know/knew) as “compression ignition, ” and it’s the basis of how a diesel engine (work/works/working). When a gasoline engine has compression ignition, we often call it “knock, ” and it can ruin the engine.
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UNIT XIII. TWO-STROKE CYCLE
Linking words and phrases
1. Read the explanations in the boxes
| Here is a way of linking clauses by expressing contrast: but, although, though, in spite of/despite, nevertheless, however, on the one hand, on the other hand, whereas, while, either…or. For example: Petrol engines use a spark plug to ignite the fuel, while diesels use compression ignition. Petrol engines run with Otto cycle, but diesel engines run with constant volume cycle. Diesel engines require heating devices to start in cold weather, however, gasoline engines do not require them. On the one hand, diesel engines produce more power than gasoline engines, onthe other hand, they produce more noise than gasoline engines. Air is mixed with fuel either through a carburetor or through a fuel-injection system. |
| Here is a way of adding information: and, both…and, also, as well, as well as, too, in addition to this, moreover. For example: Both diesel engines andgasoline engines remove products of combustion by upward movement of the piston. A steam engine can use coal as fuel, it can use wood too. Gasoline engines belong to internal combustion engines, diesel engines also belong to this group. Diesel fuel is heavier than gasoline, it is oilier as well. Diesels are widely used in stationary as well as mobile installations. |
2. a) Look through the text and guess the meaning of the underlined words.
b) Read the text and explain the title of it. Does the first sentence express the main or collateral idea?
c) Which of the linking words in bold helped you to understand that the author
a) added some information, b) contrasted the information?
The Most Commonly Used Type of Engines
The four-stroke Otto-cycle engine is widely used because it has a number of advantages over other types of engines. The for-stroke cycle is the one most commonly used for transportation as well as industrial purposes today (cars, trucks, generators, etc. ). It was invented by the French engineer, A. Beau de Rochas in 1862, and independently, by the German engineer N. Otto in 1876. The four-stroke cycle is more fuel-efficient and clean burning than the two-stroke cycle, but it requires more moving parts. Moreover, it is more easily manufactured in multicylinder configurations than the two-stroke, making it especially useful in vehicles. The later invented Wankle engine has four similar phases, however, it is a rotary combustion engine rather than much more usual reciprocating engine of the four-stroke cycle.
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