托福阅读练习：海水盐度

今天留学监理网为同学们整理准备的托福阅读练习：海水盐度，一起来看一下吧。　　

  If the salinity of ocean waters is analyzed, it is found to vary 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 —— conversion of liquid water to water vapor. In this manner, the salinity is increased, since the salts stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind.

　　The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted 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 or runoff.

　　Normally, in tropical 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 course, when this ice melts, it will tend to decrease the salinity of the surrounding water.

　　In the Weddell Sea, off Antarctica, the densest water in the oceans 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 portions of the oceans of the world.　　

Question 41-50

4l. What does the passage mainly discuss?　　

(A) The elements of salt　　

(B) The bodies of water of the world　　

(C) The many forms of ocean life　　

(D) The salinity of ocean water

42. The word "this" in line 5 refers to　　

(A) ocean　

(B) evaporation　　

(C) salinity　　

(D) crystals　　

43. According to the passage, the ocean generally has more salt in　　

(A) coastal areas　　

(B) tropical areas　　

(C) rainy areas　　

(D) turbulent areas　　

44. All of the following are processes that decrease salinity EXCEPT　　

(A) evaporation　　

(B) precipitation　　

(C) runoff　　

(D) melting　　

45. Which of the following statements about the salinity of a body water can best be　　inferred from the passage?　　

(A) The temperature of the water is the most important factor.　　

(B) The speed with which water moves is directly related to the amount of salt.　　

(C) Ocean salinity has little effect on sea life.　　

(D) Various factors combine to cause variations in the salt content of water.　　

46. The word "altered" in line 16 is closest in meaning to　　

(A) determined　　

(B) changed　　

(C) accumulated　　

(D) needed　　

47. The world "it" in line 18 refers to　　

(A) sea ice　　

(B) salinity　　

(C) seawater　　

(D) manner　　

48. Why does the author mention the Weddell Sea?　　

(A) To show that this body of water has salinity variations　　

(B) To compare Antarctic waters with Arctic waters　　

(C) To give an example of increased salinity due to freezing　　

(D) To point out the location of deep waters　　

49. Which of the following is NOT a result of the formation of ocean ice?　　

(A) The salt remains in the water.　　

(B) The surrounding water sinks.　　

(C) Water salinity decreases.　　

(D) The water becomes denser.　　

50. What can be inferred about the water near the bottom of oceans?　　

(A) It is relatively warm.　　

(B) Its salinity is relatively high.　　

(C) It does not move.　　

(D) It evaporates quickly.

>>>如有任何留学相关问题，欢迎点击进行免费咨询

》》》大家可以关注我们的高端托福备考微信公众号—托福考试中心，获取更多的考试咨讯。

》》》搜索微信公众号：“yasicenter”即可关注我们的“考鸭资料库”获取更多考试资讯！

》》》更多中小学留学咨询，敬请关注--英国中小学联盟--微信公众号！

》》》更多内容还可下载芝麻留学APP获取更多新鲜有趣的留学资讯！

• 上一篇：托福阅读坏习惯如何改掉
• 下一篇：托福阅读:词汇是基础,做题讲方法

• 相关文章

  • 留学申请 要不要找留学中介
  • 出国留学费用一般要多少
  • 选择留学中介的十大误区
  • 如何选择英国留学中介
  • 最新！2020中国教育部承认的英国大学名单完整版！
  • 2021年英国TOP10大学硕士留学申请条件汇总！

• 最新问答

  查看更多>>
  • 香港留学一年的费用需要多少钱
  • 应届高三学生申请出国留学读本科的途径有哪些？如何选择？
  • 今年高考的文科生，二本线，读什么专业好？
  • 高考成绩刚过一本线，高考志愿填报和出国留学如何选择？
  • 什么是CUG完全大学指南？
  • 什么是CWUR世界大学排名？