1.Oxigen is known to have found application in medicine.
2. We want a new device to be bought for our laboratory.
3. The problem to be solved is of great importance for their research.
II. . () .
1. Moving upwards the piston pushes the water out of the cylinder.
2. The new equipment being made in this factory is efficient and reliable in operation.
3. The temperature of the oil constantly rising, we had to stop the process.
III. . .
1. If we know all the data we shall be able to make calculations in time.
2. It would be impossible to observe the life of the microorganisms without the
electron microscope.
3. If the scientists had not developed the new materials this system wouldnt have
been perfected.
IV. 1 6 .
1,2,3,4 .
HELIUM
1. In 1868, during the eclipse () of the Sun, astronomers noticed strange lines in the spectrum of the sunlight. Astronomers' noticing the lines brought them to the conclusion that the lines could not belong to any element they knew. They decided they discovered a new element which was called helium (from the Greek word for 'sun').
2. Some time passed and another important observation was made. Chemists experimenting with a gas that came out of some uranium ore found out that the light of the gas passing through a glass prism formed the spectrum lines the astronomers had noticed in the sunlight. Thus, helium having been discovered first as an element in the Sun helped scientists to find out the element 30 years later on the Earth.
3. Helium is element No 2. Of all the atoms of the Universe, 90 per centare hydrogen, and only 9 per cent are helium. All the other elements taken together are known to make only one percent.
4. As helium is very light, it is very rarely found on the Earth. Its atoms moving with very high speed, the Earth's atmosphere cannot hold them. Investigations of large planets' atmosphere resulted in finding out that it contains much helium.
5. Being at a very low temperature a solid, in common conditions helium is a light gas. For a long time scientists had difficulties in finding ways of liquifying the element. It was only in 1908 that helium was liquified. Now chemists and physicists have discovered new methods of liquifying the element and special apparatuses are reported to have been designed to produce about 100 liters of liquid helium per hour.
6. Liquid helium having boiling point very close to the absolute zero, scientists expect to discover new important facts in the world of low temperatures with its help.
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V. 5
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When was helium liquified?
4
2
I.
. ,
.
1. Lightning is known to be the worlds most colossal spark, created by the
discharge of colossal amount of static electricity.
2. We want the device to be checked beforehand.
3. For the experiment we need several electrical devices to be connected in series.
II. . () .
1. Applying this method our plant could achieve greater volume of production.
2. The new equipment having been installed, the plant could increase its output.
3. The scientist has made a number of experiments, some of them being very
important for our work.
