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回答题When you imagine the desert,you probably think of a very hot place covered with sand．Although this is a good description for many deserts, Earth' s largest desert is actually a very cold place covered with ice: Antarctica．
In order for an area to be considered a desert, it must receive very little rainfall． More specifically, it must receive an average of less than ten inches of precipitation--which can be rain,sleet, hail, or snow--on the ground every year．Antarctica, the coldest place on earth, has an average temperature that usually falls below the freezing point．And because cold air holds less moisture than warm air, the air in Antarctica does not hold much moisture at all． This is evident in the low precipitation statistics recorded for Antarctica．For example, the central part of Antarctica receives an average of less than two inches of snow every year．
The coastline of Antarctica receives a little bit more--between seven and eight inches a year． Because Antarctica gets so little precipitation every year, it is considered a desert．
When precipitation falls in hot deserts, it quickly evaporates back into the atmosphere．The airover Antarctica is too cold to hold water vapor, so there is very little evaporation．Due to this low rate of evaporation, most of the snow that falls to the ground remains there permanently, eventually building up into thick ice sheets．Any snow that does not freeze into ice sheets becomes caught up in the strong winds that constantly blow over Antarctica． These snow-filled winds can make it look as if it is snowing．Even though snowfall is very rare there, blizzards are actually very common on Antarctica．
The main purpose of paragraph 1 is to ________ A．accept a conclusion
B．introduce an argument
C．provide a brief history
D．deny a common belief
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