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in, under, of, by
1. Selenium is ... little importance commercially. 2. It was discovered
... Berzelius. 3. This element is found... various ores. 4. The valences...
selenium arc the same as those ... sulphur. 5. It can be found ... several allotropic forms. 6. It is helpful to remember that selenium and sulphur arc very much... alike... their chemical properties. 7 proper conditions selenium can form a colloid.
Ex. 9. a) Check up if you remember the following:
fe w — немногие, немного, мало; a few — несколько
употребляются с исчисляемыми существительными
little — немного, мало; a little — немного
употребляются с нсисчислясмымн существительными
few books, little milk, a little water, a few pens, a few tables, little acid, few students, a little coffee
b) Translate the sentences into English.
1. В стакане мало воды. Принеси еще, пожалуйста. 2. Уже по здно, но в лаборатории работают несколько студентов. 3. Только не многие студенты ответили на все вопросы. 4. Вы знаете слишком мало об этом явлении. 5. На столе лежат несколько журналов. В одном из них — статья о Полинге. 6. В вашей работе есть несколько ошибок. Попробуйте их исправить. 7. Студенты нашей группы сейчас в биб лиотеке, они занимаются там уже несколько часов. 8. У меня мало денег, я не могу купить этот словарь сейчас. 9. Несколько студсн-
юв в этой группе хорошо читают по-анпшйски. 10. Вы мало работа ете, вам надо работать больше.
с) Fill in the blanks with few, afew, little, a little.
1. Only ... information is available about iodine pcntafluoridc as a solvent. 2 drops of concentrated HNOj were added to a decomposing melt containing chloride. 3. There is ... possibility that such ions can be produced under these conditions. 4. ... very interesting reactions have been shown at the lecture. 5. There arc ... published papers on the preparation and properties of inorganic deuterium compounds. 6. High-temperature reactions of polonium have been ... studied. 7. There can be
... doubt that the term “chemical structure” was used for the first time in 1861 by Butlerov. 8__ of these results have been reported previously.
Ex. 10. Translate the sentences into Russian, paying attention to modal verbs.
1. Selenium may be found in various ores. 2. We are able to describe the properties of any element looking at the periodic table. 3. Selenium can occur in several allotropic forms. 4. Chemists must remember that sulphur is a nonconductor of electricity. 5. Under proper conditions we may obtain a colloid. 6. He must be able to explain the difference between organic salts and inorganic salts. 7. Students have to understand reactions well. 8. Matter and its transformations must be studied by specialists. 9. Working in our laboratory, wc can change the state of substanccs. 10. The experiment is to be started at oncc. 11. You needn’t heat the substanccs, the reaction proceeds fast enough. 12. You should know the properties of the substanccs if you have to work with them. 13. Sometimes we needn’t accelcratc the reaction. 14. Mendeleyev was able to predict in advance the existence and properties of yet undiscovered elements. IS. Mendeleyev couldn’t be present at the meeting of Russian chemical society and had to ask Menshutkin to read the paper for him. 16. The “zero” group could be added to the periodic table only after the discovery of inert gases. 17. Wc should clean the glassware before working with it. 18. Lavoisier was able to establish his theory of combustion on the basis of the experimental results of Priestley, Shcclc and others. 19. The hydrides can decompose in water, releasing hydrogen. 20. You should remember that the yield in this reaction is good only if it goes to completion. 21. Students will be able to identify substanccs after some practice in qualitative analysis.
Ex. 11. Translate the sentences into English.
1. Селен не имеет большого промышленного значения. 2. Хотя селен не очень широко распространен, его можно найти в различных рудах. 3. Мы можем сказать, что атомный всс сслсна почти в два раза выше по сравнению с серой. 4. Из его положения в периодической таблице мы можем сделать вывод, что селен должен быть мснсс ак тивным, чем ссра. 5. Сера и селен очень похожи, и потому реакции
ссры похожи на реакции селсна. 6. Селен без запаха и без вкуса, но может иметь несколько вариаций по цвету. 7. При работе с селеном следует помнить, что у его соединения с водородом запах хуже, чем у сероводорода. 8. Удельная электропроводность селена может изме няться в соответствии с количеством падающего на него света...
Ex. 12. Make up questions to the italicized parts of the sentence.
1. Selenium was discovered by the Swedish chemist Berzelius in 1817 (4). 2. A piece of amorphous selenium is rather hard and quite brittle, just as sulphur is (2). 3. The protective colloid can prolong the life of the colloidal suspension o fselenium (3).
Ex. 13. Answer the following questions:
1. Why is there only little information about selenium in elementary textbooks? 2. Why are the properties of selenium and sulphur alike?
3. What arc the physical properties of selenium? 4. What can you say about clcctrical conductivity of selenium and sulphur? 5. In what way can we prepare a colloid with selenium? 6. How can the life of this colloid be prolonged?
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