Therearetwomainreasons   71   thetemperatureoftheair...

问题详情：

    There are two main reasons    71    the temperature of the air is always    72    (change). One reason is    73    the air around you moves in from somewhere else. Air usually moves in large bodies    74    (call) air masses. Some air masses move in from the north. These air masses usually have cold air that causes the temperature    75    (drop). Air masses also move in from the south. They usually have warmer air that causes the temperature to rise.

    Temperature changes during the day or night can be great    76    small. This depends partly   77    how many clouds are in the sky.    78    there are many clouds during the night, they act like covers on your bed. They blanket the earth and keep the air from    79    (lose) much of its    heat. The temperature usually does not drop much during such a night. When there are many clouds during    80    day, some of the sun’s energy will not reach the earth. The temperature usually does not rise much on such a day.                                                        

【回答】

  ging  73. that  ed  drop  76. or    78. When  ng  

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