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Homework. 1. Read the text and write down the sentences in which the author a) added some information, b) contrasted the information, c) explains the cause, d) shows the effect.
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Homework.
1. Read the text and write down the sentences in which the author a) added some information, b) contrasted the information, c) explains the cause, d) shows the effect.
Difference Between the Two- and Four-Stroke Engines
Most chain saws and boat motors use two-stroke engines. They have no moving valves, and the spark plug ignites the fuel each time when the piston reaches the top of its cycle. Gas and air enter through a hole in the lower part of the cylinder wall. As the piston moves up it compresses air-fuel mixture, the spark plug ignites it, and exhaust gases exit through another hole in the cylinder. Generally, a two-stroke engine produces a lot of power for its size because there are twice as many combustion cycles occurring per rotation. However, a two-stroke engine uses more gasoline and burns lots of fuel, so it is much more polluting.
2. Read the texts (A-B) and fill in the gaps with the words from the boxes
A
| downward exhaust ignites compressed uncovered fires |
You can understand a two-stroke engine by watching each part of the cycle. Start with the point where the spark plug 1__________. Fuel and air in the cylinder have been 2_____________, and when the spark plug fires the mixture 3____________. The resulting explosion drives the piston 4__________. Note that as the piston moves downward, it is compressing the air/fuel mixture in the crankcase. As the piston approaches the bottom of its stroke, the exhaust port is 5____________. The pressure in the cylinder drives most of the 6____________ gases out of the cylinder
B
| noisy smaller because therefore use hand |
The two most common type’s engines for cars are the petrol engine and the diesel engine. Petrol engines are usually lighter and 1___________ than diesel engines. This makes them cheaper and, this is why most cars 2__________ petrol engines. Petrol engines are also less 3__________ than diesel engines. They usually go faster. On the other 4___________, diesel engines use less fuel than petrol engines and, this is why trucks use them. They are also safer than petrol engines, 5___________ there is less danger of fire. There are two main types of petrol engine – 4-stroke and 2-stroke. All cars use 4-stroke engines. But most motorbikes use 2-stroke engines. They are lighter and smaller than 4-stroke engines, and are 6____________ cheaper.
UNIT XIV. TROUBLESHOOTING
Vocabulary
1. Divide into two groups and look up the meanings of the following words in dictionaries (look up only the main words and guess the meanings of their derivatives). One group should use paper dictionaries, the other group – electronic dictionaries. Which of the groups completed the task quicker?
Hole (n) – отверстие, щель
Lack (n) – недостаток, нехватка
Leak (v) протекать – leaking;
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Overhaul (n) – капитальный ремонт
Prevent (v) - предотвращать– preventing, preventive, prevention;
Proper (adj) надлежащий– properly;
Pure (adj) - чистый – purely, impurity;
Repair (n) - ремонт
Repair (v) – repairing, repaired;
Seal (n)
Seal (v) – изолировать, уплотнять– sealed, sealing;
Supply (v) – supplying, supplied;
Wear out (v) – изнашивать(ся) – worn out;
Weak (adj) - слабый– weaker, weakest, weakly
2. Pair up and learn the new words
3. Read the sentences. Put the word “repair” in each sentence in the correct form: repair or repaired,
a) An overhauled (прошедший капремонт) engine is an engine which has been removed, disassembled, cleaned, inspected and _____________.
b) Students learn disassembly, _____________, reassembly and troubleshooting procedures.
c) Both gasoline and diesel engines are studies, tested and _____________.
4. Read the sentences. Put the verb “provide” in each sentence in the correct form: provide, provides, provided
a) A two-cycle engine must be ____________ with the scavenging compressor for supplying scavenging air.
b) In a four-stroke cycle only the third stroke ____________ power to drive the crankshaft.
c) The fuel burns within the engine and __________ forces.
d) The burning of air-fuel mixture ____________ power and this power forces the piston down.
e) Fuel, ignition, cooling and lubricating systems are used in order to ______________ the proper operation of the internal combustion engine.
f) The ignition system ____________ the electric sparks that ignite the mixture.
5. Read and translate the sentences
1. Wear is a normal result of engine use.
2. The lubricating oil produces a film between the working surfaces of metal parts and reduces friction and wear.
3. The oil filters reduce engine wear.
4. In order to prevent wear and overheating, the engine has a lubrication.
5. If your spark plug or the wire leading to it is worn out, the spark will be weak.
6. If the gasket breaks down, small holes develop between the cylinder and the cylinder head, and these holes cause leaks.
7. A hole in the lower part of the cylinder wall lets in gas and air.
6. Read the explanation in the box
| Polisemic “too” Too (обычно в конце предложения) - тоже, также Too (перед прилагательным или наречием) – слишком That engine was too large, heavy and needed too much fuel. The necessity of carrying away excess heat developed by the engine has always been a problem of first importance too. |
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