1. What is cancer?

2. W

   Part VIII. Grammar

   hat causes cancer

Exercise 23: Open the brackets using Participle I or Participle II, Perfect Participle (active or passive):

1. Complex mixtures of hydrocarbon compounds (contained, containing) only carbon and hydrogen occur in very large quantities in nature.

2. In 1820 some amino acids were isolated in crystalline form from solutions (preparing, prepared) by heating proteins with mineral acid.

3. In the 20^th century the vitamins and the elements (requiring, required) only in small amounts were discovered.

4. The most important medicines (discovered, discovering) in the twentieth century are vitamins made by partial synthesis, irradiation, fermentation and other methods.

5. For the determination of vitamins B, the (testing, tested) solution was diluted with water.

6. The (colouring, coloured) matter is used in the production of some perfumes.

7. A perfume is a material (consisting, consisted) of one or more volatile constituents.

8. (Having calculated, having been calculated) the coefficients, they could write the equation of the chemical reaction.

9. (Having dissolved, having been dissolved), the substance was filtered, evaporated and dried.

10. (Having found, having been found) the necessary solvent, they purified the compound by recrystalization.

11. (having synthesized, having been synthesized ), the compound was cooled, weight and analyzed.

12. (Having purified, having been purified), silica was used as an absorbent.

13. (Having removed, having been removed) impurities, they determined the composition and structure of the synthesized compound.

14. (Having used, having been used) volatile compounds, they modified chemical surface of the solids.

15. (Having accepted, having been accepted) electrons, the ions reduced to the metallic form.

Exercise 24: Translate the sentences into Russian:

1. Grass is a green, leafy, flowering plant.

2. More than 80% of all plants living today are flowering plants.

3. A leaf is the main food-making part of a plant.

4. Fast moving water has kinetic energy.

5. Matter is changing all the time because of changing conditions in the world around us.

6. Zinc containing enzymes regulates growth, development longevity and fertility.

7. An isotope of a chemical element consists of atoms having the same number of neutrons.

8. The number of electrons revolting around the nucleus of an atom is equal to its atomic number.

9. Solutions of acids have a sour taste and produce a burning feeling when they touch skin.

10. Oxygen is a highly reactive substance, readily combining with many other elements in the process of oxidation.

11. In naturally occurring compounds, boron exists as a mixture of two stable isotopes with atomic weights of 10 and 11.

12. Salts resulting from the combination of strong acid sand weak bases will give acidic water solutions.

13. Carbon dioxide is the focus of public concern in recent years due to the increasing concentrations of this gas in the atmosphere as a result of the combustion of fossil fuels.

14. The actual volume of the molecules making up the air is only about 1/1000^th of the total volume of the gas.

Exercise 25: Suggest the English equivalents for the following words combination:

1. кипящая вода – кипяченая вода

охлаждающая жидкость – охлажденная жидкость

студенты, обсуждающие результаты теста – обсужденные тесты

осушающее вещество – осушенное вещество

окисляющий реагент - окисленная форма

выделяющий газ – выделенный газ

2. определив состав продуктов реакции – определяя плотность вещества

нагрев раствора – нагревая раствор

охладив жидкость – охлажденная жидкость

получив требуемый продукт – получая требуемый продукт

осушив кристаллы – осушая кристаллы

удаляя пары воды – удалив пары воды

разбавляя раствор – разбавив раствор

повышая концентрацию растворенного вещества – повысив концентрацию растворенного вещества

изучая законы химии – изучив основные законы химии