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(причастием, герундием, отглагольным существительным):
1.Не was looking at the plane flying overhead. 2. Wishing to learn to skate, she bought herself a pair of skates. 3. Just imagine his coming first in the race! 4. The children were tired of running. 5. Being frightened by the dog, the cat climbed a high fence.
16. Употребите сказуемое в следующих предложениях в Present Perfect Continuous (Progressive). Переведите предложения на русский язык:
Образец: Не has worked at the plant for many years.
He has been working at the plant for many years.
Он работает на этом заводе в течение многих лет.
1. They have talked for more than an hour.
2. She has taught English for ten years.
3. He has done very little work recently.
17. Переведите следующие предложения на русский язык, обращая внимание на времена группы Perfect Continuous (Progressive):
1. Не has been doing that same kind of work for many years.
2. Have you been looking through these magazines long?
18. Замените в следующих предложениях действительный залог страдательным, обращая внимание на времена группы Indefinite (Simple):
Образец: They build many new houses every year.
Many new houses are built every year.
1. They did not adopt the resolution yesterday.
2. The teacher will examine the students next week.
19. Замените в следующих предложениях действительный залог страдательным, обращая внимание на времена группы Continuous (Progressive):
Образец: They are building a new house in our street.
A new house is being built in our street.
1. They were discussing this problem when we came in.
2. The students are writing a dictation now.
20. Замените в следующих предложениях действительный залог страдательным, обращая внимание на времена группы Perfect:
Образец: They have built a new house in our street.
A new house has been built in our street.
1. Russian scientists have made many wonderful discoveries.
2. They will have published this book by the end of the year.
21. Переведите следующие предложения на русский язык, обращая внимание на употребление глагола should:
1. He should spend more time on his homework.
2. They should not make so much noise.
3. You should learn as many new words as possible.
22. Переведите текст, составьте 5 вопросов, раскрывающих основное содержание текста:
A Wonder Metal
The story of titanium is extraordinary. To begin with, it was discovered twice. A British scientist, William Gregor, found it first and called it menachanite, and six years later, in 1797, M. H. Klaproth, a German chemist, also found it and gave it its present name.
For many years, titanium was of inretest only to research chemists — it was considered too brittle to be of any practical value. Yet it was the impurities with which it was usually associated (it forms compounds easily with nearly every known element) that made it brittle.
It cost the chemists in many countries endless efforts to isolate pure titanium and even more to start producing it commercially. In 1948 the world stock of pure titanium was only ten tons. Today the output is much larger.
Titanium has one surprising property — it is completely inert in biological media, something the medical community was quick to notice. It is being used to make artificial joints and many other things necessary in surgery at the Priorov Central Institute of Traumatology and Orthopedics. Titanium instruments do not corrode, and are thirty per cent lighter than instruments made of stainless steel.
Titanium's high standard of corrosion resistance, lightness, tensile strength, and the ease of forging, rolling and stamping are finding it more and more uses. Titanium alloys are very useful in mechanical engineering, and for chemical and refractory apparatus. Titanium helped Soviet design engineers to surmount the sound and heat barriers in supersonic and high-altitude aircraft designing. On earth, it shows good work at chemical plants, in the pulp-and-paper and food industries. Moreover, it is still a source of surprise for the investigator.
A group of researchers at our Institute, under the leadership of Professor. I. IKornilov, D. Sc. (Chemistry), produced a material that has a kind of "memory", as the following experiment shows: a thin bent strip of the new alloy was clamped to a stand, a 500-gram weight hung on the free end. A current was passed through for several seconds, which heated the strip to more than 100 °C. As if commanded by an enigmatic force, it straightened out like a tight spring and lifted the load. When the current was switched off, the strip gradually went back to its original shape. The cycle was repeated a number of times, and the strip always "remembered" its original shape. The surprising phenomenon of direct conversion of thermal energy into mechanical is seen with the naked eye.
The explanation is in the crystalline modifications of titanium-nickel alloy which, changing with the temperature, also changes back again.
This is why the material has a "memory" and special acoustic properties. At room temperature, the alloy called titanium nickeloid becomes soft, ductile and does not produce the characteristic metallic sound when struck. However, when it is heated to a certain temperature, it becomes hard, resilient and ringing.
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