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老托福阅读100篇之水循环

时间：2015-08-19 17:04:50 / 编辑：Lee

　　老托福阅读100篇相对TPO要简单一些，也是伴随托福备考学员的很重要的一份资料，对于基础薄弱，做TPO真题阅读需要过渡的考生来说再适合不过了，今天一诺留学小编给大家分享的是老托福阅读100篇之水循环，希望考生认真练习。

　　水循环

　　The geology of the Earth's surface is dominated by the particular properties of water. Present on Earth in solid, liquid, and gaseous states, water is exceptionally reactive. It dissolves, transports, and precipitates many chemical compounds and is constantly modifying the face of the Earth.

　　Evaporated from the oceans, water vapor forms clouds, some of which are transported by wind over the continents. Condensation from the clouds provides the essential agent of continental erosion: rain. Precipitated onto the ground, the water trickles down to form brooks, streams, and rivers, constituting what are called the hydrographic network. This immense polarized network channels the water toward a single receptacle: an ocean. Gravity dominates this entire step in the cycle because water tends to minimize its potential energy by running from high altitudes toward the reference point, that is, sea level.

　　The rate at which a molecule of water passes though the cycle is not random but is a measure of the relative size of the various reservoirs. If we define residence time as the average time for a water molecule to pass through one of the three reservoirs ¡ª atmosphere, continent, and ocean ¡ª we see that the times are very different. A water molecule stays, on average, eleven days in the atmosphere, one hundred years on a continent and forty thousand years in the ocean. This last figure shows the importance of the ocean as the principal reservoir of the hydrosphere but also the rapidity of water transport on the continents.

　　A vast chemical separation process takes places during the flow of water over the continents. Soluble ions such as calcium, sodium, potassium, and some magnesium are dissolved and transported. Insoluble ions such as aluminum, iron, and silicon stay where they are and form the thin, fertile skin of soil on which vegetation can grow. Sometimes soils are destroyed and transported mechanically during flooding. The erosion of the continents thus results from two closely linked and interdependent processes, chemical erosion and mechanical erosion. Their respective interactions and efficiency depend on different factors.

　　1. The word "modifying" in line 4 is closest in meaning to

　　(A) changing

　　(B) traveling

　　(D) destroying

　　2. The word "which" in line 5 refers to

　　(A) clouds

　　(B) oceans

　　(D) compounds

　　3. According to the passage , clouds are primarily formed by water

　　(A) precipitating onto the ground

　　(B) changing from a solid to a liquid state

　　(D) being carried by wind

　　4. The passage suggests that the purpose of the "hydrographic network" (line 8) is to

　　(A) determine the size of molecules of water

　　(B) prevent soil erosion caused by flooding

　　(D) regulate the rate of water flow from streams and rivers

　　5. What determines the rate at which a molecule of water moves through the cycle, as discussed in the third paragraph?

　　(A) The potential energy contained in water

　　(B) The effects of atmospheric pressure on chemical compounds

　　(D) The relative size of the water storage areas

　　6. The word "rapidity" in line 19 is closest in meaning to

　　(A) significance

　　(B) method

　　(D) reliability

　　7. The word "they" in line 24 refers to

　　(A) insoluble ions

　　(B) soluble ions

　　(D) continents

　　8. All of the following are example of soluble ions EXCEPT

　　(A) magnesium

　　(B) iron

　　(D) calcium

　　9. The word "efficiency" in line 27 is closest in meaning to

　　(A) relationship

　　(B) growth

　　(D) effectiveness

　　答案：AACCD CABD

　　以上内容就是老托福阅读100篇之水循环的介绍，希望对大家的托福考试有帮助。如需了解更多留学考试的相关信息，欢迎拨打一诺留学的免费热线400-003-6508或者010-62680991进行出国留学咨询，或者点击一诺留学官方网站http://www.yinuoedu.net/页面的“在线咨询”与一诺留学专家直接对话。