Раскройте скобки и употребите глаголы в соответствующей форме. 1. mixed economy is an economic system in which some industries (to own) by the state and others (to own) by private persons and firms. 2. when supply is increased, a larger amount (to offer) at a given price. 3. the supply of agricultural products cannot be (to increase) within a very short period of time. 4. the aim of the organization of petroleum (to export) countries (opec) (to found) in 1961 is to maintain a standard price for oil and, if necessary, to limit output. in 1973 the opec suddenly (to begin) to use its influence (to raise) the world price of oil so that by the end of 1974 the price (to rise) three times in most (to import) countries. it(to increase) many times since then. 5. marginal revenue is the additional revenue (to earn) by a producer from selling one more unit of his product. 6. money supply is the total amount of money (to hold) by all persons and organizations in a country at a particular time. 7. the revenue (to obtain) from selling output depends on the demand. 8. landless farmers, that is, farmers (to own) no land, have to cultivate land (to own) by others. 9. economists use the word «capital» for goods not entirely (to use) up in the production process, during a particular period. electricity is not «capital» as it (to use) entirely in the production process. 10. with less risk of a fall of price between the time decisions (to make) and commodities (to sell), producers will use additional inputs. 11. supply (to depend) on output prices and input prices. an increase in the price of an input (to result) in a reduced use of that input. a reduction in the price of an output (to have) the same effect as an increase in the price of input, that is, a reduced use of input. the input use (not to change), provided output and input prices (to rise) or (to fall) by an equal percentage. thus, the effect on output of a decrease in product prices (can) (to be neutralized) by an equal percentage decrease in input prices. sometimes the prices of inputs and outputs (to change) together. for example, a fall of livestock product prices (to reduce) the demand for feed grains. this (to lead) to a fall in the price of feeds, that is, the price of inputs.