1. define the tense and the voice a) the letters have been sent this week. b) yesterday the room was cleaned very well. c) he usually wakes his children up at 6 a.m. d) i shall give advice to you a bit later. e) last year a new house was built near the park. f) football is played almost everywhere. g) a new shopping centre will be built here next year. h) i have just read the text. 2. change the sentences into the passive voice a) they visited that museum last year. b) he will publish his first book in a year. a) they closed the supermarket at 7 p.m. yesterday. b) we often visit disco clubs.

When i was a child i liked to borrow books from libraries. at first i was afraid to go there without my parents because there were always many people in the library. besides, it was difficult for me to choose an interesting book without help. but then my mum advised me to ask librarians to help me and i began to go to the library regularly. when i needed a book by a definite author i asked librarians to bring it to me or to show where i can find it. some books were easily found, the others were impossible to get. i was sorry if i could not get the nesessary book and left the library in low spirits. nowadays we may find literature not only in the libraries but in the internet as well. it is easier and more convenient. so, i hope that due to it people will read more good books.

1. mixed economy is an economic system in which some industries (are owned) by the state and others (are owned) by private persons and firms. 2. when supply is increased, a larger amount (is offered) at a given price. 3. the supply of agricultural products cannot be (increased) within a very short period of time. 4. the aim of the organization of petroleum (exporting) countries (opec) (founded) in 1961 is to maintain a standard price for oil and, if necessary, to limit output. in 1973 the opec suddenly (began) to use its influence (raising) the world price of oil so that by the end of 1974 the price (had risen) three times in most (importing) countries. it (has increased) many times since then. 5. marginal revenue is the additional revenue (earned) by a producer from selling one more unit of his product. 6. money supply is the total amount of money (held) by all persons and organizations in a country at a particular time. 7. the revenue (obtained) from selling output depends on the demand. 8. landless farmers, that is, farmers (owning) no land, have to cultivate land (owned) by others. 9. economists use the word «capital» for goods not entirely (used) up in the production process, during a particular period. electricity is not «capital» as it (is used) entirely in the production process. 10. with less risk of a fall of price between the time decisions (are made) and commodities (are sold), producers will use additional inputs. 11. supply (depends) on output prices and input prices. an increase in the price of an input (results) in a reduced use of that input. a reduction in the price of an output (has) the same effect as an increase in the price of input, that is, a reduced use of input. the input use (won't change), provided output and input prices (rise) or (fall) by an equal percentage. thus, the effect on output of a decrease in product prices (can be neutralized) by an equal percentage decrease in input prices. sometimes the prices of inputs and outputs (change) together. for example, a fall of livestock product prices (reduces) the demand for feed grains. this (leads) to a fall in the price of feeds, that is, the price of inputs.