五,阅读文章,根据文章内容,完成句子(共6小题;每小题1分,满分6分)Theairaroundtheearthiscalledatmosphere.It'suptomorethan600mileshigh.Airplanesflyonlyafewmileshighintheair.Theatmospheremakesthetemperature

Question

五,阅读文章,根据文章内容,完成句子(共6小题;每小题1分,满分6分)
The air around the earth is called atmosphere.It's up to more than 600 miles high.Airplanes fly only a few miles high in the air.The atmosphere makes the temperature on the earth so good that a great number of living things can stay alive.
Air is all around us.Air is a mixture of gases(气体) that we can not see.About one fifth of the air is oxygen,which is needed by all living things.About four fifths of the air is nitrogen(氮).Plants need it to live.There are other gases in the air.The most important among them is carbon dioxide.Green plants use carbon dioxide to make food.People give off carbon dioxide when they breathe.
Air has weight and takes up space.Air pressure (压力) inside our body is almost the same as air pressure outside.Because of this balance,we don't feel the pressure of the air on us.
Since the sun's heat affects the earth's air,the weather conditions on the earth change greatly:warm or hot; cool or cold; sunny or cloudy; windy,rainy,or snowy.
When temperature changes,what happens to the air When air is being heated,it expands(膨胀).That means it takes up more space.When air is being cooled,it takes up less space,or contracts(收缩).
55.We call the air around the earth .
56.About twenty percent of the air is .
57.When people breathe,they give off ,which is used to make food by green plants.
58.Although air has ,we don't feel its pressure on us.
59.The weather on the earth is changeable because of .
60.When the air temperature gets higher,the air .

Answer 1

55.atmosphere
56.oxygen
57.carbon dioxide
58.weight
59.the sun's heat
60.expands