3. Перепишите следующие предложения, определите в них функ­цию инфинитива и письменно переведите предложения на русский язык.

1. He pretended to be sleeping.

2. It is useless to discuss this question.

3. To walk in the garden was very pleasant.

4. Заполните пропуски необходимыми артиклями.

1. There was . . . knock on . . . door. I opened it and found . . . small dark man in . . . blue overcoat and . . . woollen cap.

2. He said he was . . . employee of . . . gas company and had come to read . . . meter.

3. But I had . . . suspicion that he wasn't speaking . . . truth because . . . meter readers usually wear . . . peaked caps.

4. However, I took him to . . . meter, which is in . . . dark corner under . . . stairs.

5. I asked if he had . . . torch; he said he disliked torches and always read . . . meters by . . . light of . . . match.

5. Перепишите следующие предложения, определите в них видовременные формы и залог глаголов-сказуемых и укажите их инфинитив; переведите предложения на русский язык.

a) 1. Russian chemical science is successfully solving many complex problems.

2. Some decades later this forgotten fact came to the knowledge of chemists.

3. By the end of this academic year we shall have finished our research

b) 1. Some experiments will be made by our professor to illustrate his report.

2. Elements have been classed according to their valence

3. Some effective medicines are being prepared at that laboratory.

6. Перепишите предложения и поставьте: 1) общий вопрос к нему; 2) специальный вопрос ко всем членам предложения.

In a few years Mendeleyev was elected an honorary member of several academies of sciences.

7. Перепишите следующие предложения; подчеркните в них Participle I, Participle II, Gerund и установите функции каждого из них, т.е. укажите, является ли оно (он) определением, обстоятельством или частью сказуемого. Переведите предложения на русский язык.

1. Having built the house, he began building a greenhouse.

2. When writing letters, he doesn’t like to be disturbed.

3. The dog carried by the child gave a sharp yelp.

4. That day we stayed at home watching TV.

8. Перепишите следующие предложения; подчеркните в каждом из них модальный глагол или его эквивалент. Переведите предложения на русский язык.

1. You should do as you are told.

2. I could run very fast when I was a boy.

3. It might rain this afternoon.

4. You are permitted to smoke here.

9. Переведите предложения.

1. Можно мне здесь подождать?

2. Студенты получают эти книги в библиотеке.

3. Друзья моего брата хорошо говорят по-немецки.

10. Прочитайте и письменно переведите тек­ст.

Alkaloids

1. It is from those plants containing alkaloids that a large number of drugs are derived. The group, however, is a very varied one and it is only the chemical properties of a basic nitrogen that unify the many classes of alkaloids. For this reason questions of the physiological role of alkaloids in the plant, their importance in taxonomy and biogenesis are discussed at the level of a particular class of alkaloids.

2. A precise definition of the term "alkaloid" is somewhat difficult because there is no clear • out boundary¹ between alkaloids and naturally occurring complex amines. Typical alkaloids are sure to be derived from plant sources they are basic, they contain one or more nitrogen atoms (usually in a heterocyclic ring) and they usually have a marked physiological action on man or animals. The name "photo-alkaloid" or "ammo-alkaloid" is sometimes applied to compounds such as hordenine, ephedrine and coichicine which lack one or more of the properties of typical alkaloids. In practice alkaloids proved to be substances present in plant and giving the standard qualitative tests.

3. Most alkaloids are well defined crystalline substances which unite with acids to form salts. In the plant they may exist in the free state, as salts or as N-oxides. In addition to the elements carbon, hydrogen and nitrogen, most alkaloids are known to contain oxygen. A few, such as coniine from hemlock² and nicotine from tobacco, are oxygen-free and are liquids. Although coloured alkaloids are relatively rare, they are not unknown, berberine, for example, is yellow and the salts of sanguinarine are copper-red.

4. Knowledge of the solubility of alkaloids and their salts is of considerable pharmaceutical importance. Not only are alkaloidal substances often administered in solution, but also the differences in solubility between alkaloids and their salts provide methods for the isolation of alkaloids from the plant and their separation from the nonalkaloidal substances also present. The free bases are usually only slightly soluble in water but soluble in organic solvents. With salts the reverse is often the case, these being usually soluble in water but sparingly soluble in organic solvents.

5. Most allcaloids are precipitated from neutral or slightly acid solutions by Maker's reagent (potassiomercuric iodine solution), by Wagner's reagent (solution of iodine in potassium iodide), by solution of tannic acid, by Hager's reagent (saturated solution of picric acid), by solution of phosphomolybdic acid and by Dragendorff’s reagent (solution of potassium bismuth iodide). These precipitates may be amorphous or erystaliine and are of various colours: cream (Mayer's), yellow (Hager's) reddish-brown (Wagner's and Dragendorffs). Other plant constituents such as proteins also give precipitates with several of the above reagents, so the tests are often unreliable when applied directly to a plant extract.

6. Alkaloid extraction methods vary with the scale, purpose of the operation and with the raw material. For many research purposes chromatography gives both speedy and accurate results. However if an appreciable quantity of pure alkaloid is required, two general methods will usually serve. Both of these are based on the fact that free alkaloidal bases are usually but sparingly soluble in water but soluble in organic solvents. Precipitation of alkaloids is carried out with organic solvents such as ether or petroleum spirit. The concentrated organic liquid is then shaken with aqueous acid and allowed to separate. Alkaloidal salts will precipitate in the aqueous layer, while many impurities remain behind in the organic solvent.

ВАРИАНТ 7

1. Перепишите следующие предложения. Определите по грам­матическим признаках, какой частью речи являются слова, оформ­ленные окончанием s, и какую функцию это окончание выполняет.

Переведите предложения на русский язык.

1. My father has gone to the chemist’s.

2. These are children’s books.

3. The surface of the Eart5h looks wonderful from space.

2. Перепишите следующие предложения и переведите их, обра­щая внимание на особенности перевода на русский язык определений, выраженных именем существительным.

1. Is this a tea cup? May I take it?

2. Sport exercises are very useful to health.

3. A kitchen clock is made of plastic.