首页
财务会计
医药卫生
金融经济
考公考编
外语考试
学历提升
职称考试
建筑工程
IT考试
其他
登录
职称考试
Water The second most important constituent (构成成分)of the biosphere (生物圈)is...
Water The second most important constituent (构成成分)of the biosphere (生物圈)is...
admin
2020-12-24
38
问题
Water
The second most important constituent (构成成分)of the biosphere (生物圈)is liquid water. This can only exist in a very narrow range of temperatures, since water freezes at 0℃ and boils at 100℃. Life as we know it would only be possible on the surface of a planet which had temperatures somewhere within this narrow range.
The earth’s supply of water probably remains fairly constant in quantity. The total quantity of water is not known very accurately, but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers. Most of it is in the form of the salt water of the oceans — about 97 percent. The rest is fresh, but three-quarters of this is in the form of ice at the Poles and on mountains, and cannot be used by living systems until melted. Of the remaining fraction, which is somewhat less than one percent of the whole, there is 10 ?20 times as much stored underground water as there is actually on the surface. There is also a tiny, but extremely important fraction of the water supply which is present as water vapour in the atmosphere.
Water vapour in the atmosphere is the channel through which the whole water circulation (循环)of the biosphere has to pass. Water evaporated (蒸发)from the surface of the oceans,from lakes and rivers and from moist (潮湿的) earth is added to it. From it the
water comes out again as rain or snow, falling on either the sea or the land. There is, as might be expected,a more intensive evaporation per unit area over the sea and oceans than over the land, but there is more rainfall over the land than over the oceans, and the balance
is restored by the runoff from the land in the form of rivers.
The word "fraction" in the second paragraph means
选项
A a very small amount.
B a large area.
C an important system.
D a major source of information
答案
A
解析
转载请注明原文地址:https://ti.zuoweng.com/ti/3CsQKKKQ
相关试题推荐
共用题干 第二篇GoodTableMannersMannersplayanimportantpartinmakingafavorab...
共用题干 第二篇GoodTableMannersMannersplayanimportantpartinmakingafavorab...
AnimportantpartofthenationalgovernmentistheForeignService,abranch...
TheMeanhgofDreams 1Dreamsplayanimportantroleinourlives.Iftheyc...
TheMeanhgofDreams 1Dreamsplayanimportantroleinourlives.Iftheyc...
TheMeanhgofDreams 1Dreamsplayanimportantroleinourlives.Iftheyc...
TheMeanhgofDreams 1Dreamsplayanimportantroleinourlives.Iftheyc...
FoodSafetyandFoodborneIllness Foodsafetyisanincreasinglyimportant...
FoodSafetyandFoodborneIllness Foodsafetyisanincreasinglyimportant...
FoodSafetyandFoodborneIllness Foodsafetyisanincreasinglyimportant...
随机试题
既可用作注射剂的抑菌剂,又可用作注射剂的镇痛药的是 A.乙醇 B.苯甲酸
棘波节律可见于()。 A.失神发作 B.不典型失神发作 C.过度换气反应
例会制度的优点不包括()。 A.信息不易受到歪曲 B.沟通具有亲切感 C
心脏瓣膜病变中,最多见的是 A、二尖瓣病变 B、三尖瓣病变 C、主动脉
按信托性质分类,房地产投资信托基金的类型有()。
根据《规划环境影响评价条例》编制综合性规划,应编写“环境影响篇章或者说明”。“环
下列表述中哪一项是正确的?
某工程项目的装饰工程可以分解为
1998-139.功能宣发或肃降肺气、利尿消肿的药是 A.麻黄B.黄芪C.
足三阴经在内踝8寸以下的分布规律是A.太阴在前,厥阴在中,少阴在后B.太阴在前,少阴在中,厥阴在后C.厥阴在前,太阴在中,少阴在后D.厥阴在前,少阴在中,