11. A) Find in ex. 2 and ex. 5 all the sentences containing infinitive, participle (I and II) and gerund. Translate these sentences into Russian.

b) Translate the following text into English paying attention to the italicized parts of the sentences:

При нормальных условиях кислород представляет собой бесцветный газ, не имеющий запаха и состоящий из двухатомных молекул. Дня получения кислорода в лабораторных условиях используется несколько методов. Кислород является сильным окислителем и, соединяясь со многими элементами, образует оксиды. Реакции образования оксидов экзотермичны (exothermic), и это во многих случаях может приводить к возгоранию соединяющегося с кислородом элемента, либо образующего соединения.

Кислород и его соединения необходимы для поддержания жизни. Они играют важнейшую роль в процессах обмена веществ и дыхания.

Озон — это один из аллотропов (allotrope) кислорода. Это голубой газ, обладающий небольшой растворимостью в воде. При низких концентрациях он нетоксичен, но при концентрациях, превышающих 100 миллионных долей, становится токсичным.

Озон реагирует с алкенами (alkene), расщепляя (to split) их двойные связи (bond) в процессе, известном как озонолиз (ozo-nolysis), и образуя органические соединения, которые называются озонидами (ozonide).

12. Listen to the following dialogue and say what problems the participants are discussing. The notes and words will help you to understand the text better: notes

1. don't follow me — не успеваете за мной

2. to begin with — начнем с того, что

3. you mean — вы имеете в виду

4. it's not as simple as that — не так все просто

5. it should be noted — следует отметить

6. sorry to interrupt — простите, что перебиваю

7. absolutely true — абсолютно верно

8. I have a point to make here — здесь я хочу сказать

9. as far as I know — насколько я знаю

10. to a large extent — в большой степени

11. to tell you the truth — по правде говоря

12. see you later — до встречи

WORDS

abundant — распространенный odour — запах

approximately — приблизительно outstanding — выдающийся

colour — цвет pale — бледный

to compress — сдавливать, сжимать

slightly — слегка, немного

dust — пыль supporter — сторонник; зд. тот, кто поддерживает

main — главный, основной

negligible — незначительный taste — вкус

С. S.: Good afternoon. I'm Carl Spider and today we're going to discuss oxygen. If you don't understand or follow me, or if you have anything to add, you're welcome to interrupt. O.K.? Well, to begin with, it's common knowledge, oxygen is the most abundant element on our planet...

STUDENT 1: May I interrupt you for a moment? When was it isolated?

C. S.: You mean discovered? That's a good question. Well, it was discovered by Priestley as early as 1774. But it's not as simple as that. Because Lavoisier also made experiments with oxygen isolating it from air and developing Priestley's work. Lavoisier emphasized the role of oxygen in combustion and respiration. Well, coming back to what I was saying, in nature oxygen may occur in a free state or may be found combined with other elements. It should be noted, that because of its chemical properties it has been called the most important of all elements to man.

STUDENT 2: Sorry to interrupt you, but is it because of being a sup­porter of combustion and of forming oxides with both metals and nonmetals?

C. S.: Quite right. Let me continue and say that oxygen is a colourless, odourless, tasteless gas. It's slightly heavier than air and is slightly soluble in water. Being com­pressed and cooled it can form a pale blue liquid boiling at -192.98°C which would be slightly magnetic.

STUDENT 1: I wonder if I could comment on the chemical property ofoxygen?

С. S.: Please.

STUDENT 1: Well, the outstanding property of oxygen is its activity. Correct? In other words, its tendency to combine with other substances.

C. S.: Absolutely true. It will combine with all the elements.

STUDENT2: I have a point to make here...

C. S.: Yes?

STUDENT2: As far as I know, it doesn't combine with inert gases, does it?

C. S.: Yes, quite correct. Before I could resume, would you answer my question? What happens to oxygen with the increase in temperature?

STUDENT2: I guess, it would greatly increase the oxygen's activity. C. S.: Yes, that's true. Now, oxygen, silicon, aluminium and hydrogen together constitute approximately 80 percent of the Earth's crust, sea and atmosphere.

STUDENT I: May I interrupt you again, Dr. Spider? What about nitrogen?

C. S.: Oh, yes. It's the main element in the air, but it isn't one of the most common elements...

STUDENT 2: Could I say something about nitrogen?

C.S.: I'd be delighted to hear.

STUDENT 2: Nitrogen forms only a small percentage of the crust and oceans, and the mass of the atmosphere is negligible compared to the total mass of the Earth.

C. S.: That's a good comment, I should say. Speaking about air, could anybody tell me about its composition?

STUDENT 1: Oh, it varies and depends to a large extent on plants and animals which control the amounts of oxygen and carbon dioxide by photosynthesis and respiration.

C. S.: Good. What else does air contain? Anybody?

STUDENT 2: Water vapour and dust. If dust is removed, then. to tell you the truth, I don't remember the exact figures...

C. S.: Well, the approximate composition by volume is the following: nitrogen — 78 percent, oxygen — 21 percent, argon — 0.93 percent, carbon dioxide — 0.03 percent, plus small quantities of other gases. Well, thank you for your active participation. Next time we'll speak about combination of oxygen with metals. What do they form?

STUDENT2: Oxides, I suppose.

C. S.: Well done! See you later.

13. a) Listen to the dialogue again and say who of the students is the most active in the conversation. What makes you think so?

b) Listen to the dialogue once more and answer the questions in it. Your 'teacher will stop the tape after each questions.

14. Listen to the conversation again and say in which situations a) the students interrupt the lecturer and what expressions they use to do this; b) the lecturer agrees with the students and approves of their contribution using the expressions of agreement and approval. What are they? c) are there any expressions of emphasis a certainty in the dialogue?

15. What parts of Dr. Spider's explanation would you develop having in mind the latest knowledge about air, atmosphere and gases?

16. Read another text on the same problem and say what ideas can be found in it that are the same in the 1st text and the dialogue. Which information presented in this text is not found in the others? Pay attention to the sentences in brackets which have been condensed to show you how the verbals may be used.

REACTIONS OF OXYGEN

No other element is more important to life than oxygen. It is not only the most widely distributed element on the surface of the globe, but it is absolutely necessary to the maintenance of life. (It is the most widely spread element on the surface of the globe, and it is necessary to maintain life.) To be sure, air breathing animals would die within a few minutes if the supply of oxygen in the atmosphere stopped suddenly. (Air breathing animals would die very quickly, if the supply of oxygen in the atmosphere stopped.) After we have learned the methods of oxygen's preparation, let us study its main reactions. (Having learned the methods of oxygen's preparation, let us study its main reactions.) When oxygen combines with an element, it forms a product which is called an oxide. (Combining with an element, oxygen forms a product called an oxide.) The process is called oxidation. There are only a few elements which are attacked by oxygen. (There are only a few elements attacked by oxygen.) Among the substances which are unaffected by it we should mention inert gases. (Among the substances unaffected by it mention should be made of the inert gases.) Combinations with oxygen often liberate heat and light in which case the process is known as combustion. (Combinations with oxygen often liberate heat and light and this process is known as combustion.) There are some elements which do not catch fire unless they are heated. (There are some elements not catching fire unless heated.) Some substances will ignite even if they are very slightly heated; others have to be heated before they take fire. (Some substances will ignite even if slightly heated; others have to be heated before taking fire.) The temperature at which a substance ignites is called its kindling point. Once these reactions are started, they liberate heat and light. (Once started, these reactions liberate heat and light.) The heat which is liberated maintains the substance at or above the kindling temperature. (The heat liberated maintains the substance at or above the kindling temperature.) The amount of heat which is liberated by very slow oxidation such as rusting of metals and the decay of wood is the same as that which is liberated by rapid combustion, but there is no rise in temperature because the heat is radiated to the surrounding air. (The amount of heat liberated by very slow oxidation (rusting and the decay of wood) and by rapid combustion is the same, but there is no rise in temperature because the heat is radiated to the surrounding air.) The difference between combustion, on the one hand, and corrosion and decay, on the other, is one of the rates of reaction and temperature at which these reactions take place. (The difference between combustion and corrosion and decay is one of the rates of reaction and temperature at which these reactions take place.) ,