Because agriculture is so important to a nation’s well-being, governments have always been concerned with it. For example, the United States and Canada have long produced surpluses that complicate their economies. Surpluses tend to lower prices to farmers and seriously endanger the agriculture industry. Governments have instituted systems of price supports to maintain a fair price when surpluses cause prices to drop. The system in the United States is a good example. A government program supports the prices paid to farmers for grains, and other agricultural products.
Support prices are based on parity, which is the ratio between the prices farmers receive for their crops and the prices they must pay for things they need. The government selected the period from 1910 to 1914 as a time when farm prices were in a fair ratio with farming costs. This is the base period now used to determine parity prices.
The idea is to assure farmers that what they get for a bush
A. they throw the country into great disorder
B. they entail more expenditure on the part of the government
C. they usually involve direct governmental support price
D. the government has to set up special pricing systems
Space is a dangerous place, not only because of meteors(流星)but also because of rays from the sun and other stars. The atmosphere again acts as our protective blanket on earth. Light gets through, and this is essential for plants to make the food which we eat. Heat, too, makes our environment endurable. Various kinds of rays come through the air from outer space, but enormous quantities of radiation(辐射) from the sun are screened off. As soon as men leave the atmosphere they are exposed to this radiation but their spacesuits or the walls of their spacecraft, if they are inside, do prevent a lot of radiation damage.
Radiation is die greatest known danger to explorers in space. The unit of radiation is called" rem". Scientists have reason to think that a man can put up with far more radiation than 0.1 rem without being damaged; the figure of 60 rems has been agreed on. The trouble is that it is extremely difficult to be sure about radiation damage--a person may feel
A. the Apollo mission was very successful
B. protection from space radiation is not a easy job
C. astronauts will have deformed children or grandchildren
D. radiation is not a threat to well-protected space explorers
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