2. 公务员
  3. When we analyze the salt salinity(盐浓度)of ocean waters，we find that it varies only slightly from place to place．Nevertheless，some

When we analyze the salt salinity(盐浓度)of ocean waters，we find that it varies only slightly from place to place．Nevertheless，some

admin2014-02-25  43
问题   When we analyze the salt salinity(盐浓度)of ocean waters，we find that it varies only slightly from place to place．Nevertheless，some of these small changes are important．There are three basic processes that cause a change in oceanic salinity．One of these is the subtraction of water from the ocean by means of evaporation．In this manner，the salinity is increased，since the salt stays behind．If this is carried to the extreme，of course，white salt would be left behind；this，by the way，is how much of the table salt we use is actually obtained．
  The opposite of evaporation is precipitation，such as rain，by which water is added to the ocean．Here the ocean is being diluted(稀释)SO that the salinity is decreased．This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean．Thus salinity may be increased by the subtraction of water by evaporation，or decreased by the addition of fresh water by precipitation．
  Normally，in hot regions where the sun is very strong，the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation．Similarly，in coastal regions where rivers dilute the sea，salinity is somewhat lower than in other oceanic areas．
  A third process by which salinity may be altered is associated with the formation and melting of sea ice．When seawater is frozen，the dissolved materials are left behind．In this manner，seawater directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared．Of coulee，when this ice melts，it will tend to decrease the salinity、of the surrounding water．
    In the Weddell Sea，the densest water in the ocean is formed as a result of this freezing process，which increases the salinity of cold water．This heavy water sinks and is found in the deeper portion of the oceans of the world．
It can be known from the passage that increase in the salinity of ocean water is caused by( )
选项 A、melting of sea ice
B、precipitation
C、evaporation
D、supplement of salt
答案C
解析 通过第一段中“…by means of evaporation．In this manner，the salinity is increased，since the salt stays behind”可知要使海水的盐浓度变大，可以通过蒸发。故答案选C。
转载请注明原文地址:https://www.kaotiyun.com/show/G06q777K
本试题收录于： 中学英语题库教师公开招聘分类
0

中学英语

教师公开招聘

相关试题推荐
随机试题
最新回复(0)