2017年12月17日托福考试阅读真题及解析

2017年12月17日托福阅读真题，小编整理了文章的梗概，考生可以通过阅读文章的概要简单了解阅读考查要点。接下来，大家详细了解一下2017年12月17日托福阅读真题及解析内容。

　　2017年12月17日托福阅读真题-Passage One

　　学科分类：地质学

　　题目：Glacier Effect

　　内容回忆：

第一段讲冰川对陆地的影响很大。冰川的重量会使大陆表面下降，这个过程时间很长，然后地球表面又要用很久的时间恢复原来的高度。比如Husdon和 Great lake现在就在慢慢恢复回上次冰川世纪前的高度。

第二段讲冰川的移动，随着冰川越来越大，收到重力的影响，会慢慢移动。移动的过程中，会切割岩石，推倒树木，摧毁遇到的一切植被生物。

第三段讲到在平坦的地方形成的冰川会移动缓慢，朝各个方向发展。而在山谷形成的冰川，因为垂直的角度大，所以会形成V形冰川。而原本是V形山谷 会形成U冰川。当冰川融化后，会变成坡度很大的地形。很多现在的瀑布就是这么来的。最后一段说到冰川会形成很多地形，比如horn , ridge。

　　托福机经命中：2017年16&17日托福阅读预测地质类第一题

　　词汇题：

in response to=as a result of

depositing=putting

sculpt=shape

drastic=very significant

　　Thermal Stratification

Physical characteristics of aquatic environments at different depths such as salt level, light, inorganic nutrients, degree of acidity, and pressure all play key roles in the distribution of organisms. One of the most important physical features is thermal stratification.

When solar radiation strikes water, some is reflected, but most penetrates the surface and is ultimately absorbed. Although water may appear transparent, it is much denser than air and absorbs radiation rapidly. In clear water, 99 percent of the solar radiation is absorbed in the upper 50 to 100 meters. Longer wavelengths of light are absorbed first; the shorter wavelengths (which have more energy) penetrate farther, giving the depths their characteristic blue color.

This rapid absorption of sunlight by water has two important consequences. First, it means that photosynthesisthe process by which plants use the energy of sunlight to produce the organic carbon compounds necessary for lifecan only occur in surface waters where the light intensity is sufficiently high. Species that produce their own organic carbon compounds are called primary producers, and they are the base of the marine food web. Virtually all of the photosynthesis that supports the rich life of oceans and lakes comes from plants living in the upper 10 to 30 meters of water. Along shores and in very shallow bodies of water, some species such as kelp are rooted to the bottom. These plants may attain considerable size and structural complexity, and may support diverse communities of organisms. In the open waters that cover much of the globe, however, the primary producers of organic carbon are tiny，often one-celled algae (called phytoplankton), which are suspended in the water. Zooplankton, tiny invertebrates that feed on phytoplankton, migrate vertically on a daily cycle: up into the surface waters at night to feed and down into the dark，deeper waters during the day to escape predatory fish that rely on light to detect prey.

Second, the rapid absorption of sunlight by water means that only surface water is heated. The density of pure water is greatest at 4jaC and declines as the water’s temperature rises above or falls below this point. When solar radiation heats the water surface above 4° C, the warm surface water becomes lighter than the cool, deeper water, and so tends to remain on the surface，where it may be heated further and become even less dense. In tropical areas and in temperate climates during the summer，the surfaces of oceans and lakes are usually covered by a thin layer of warm water. Unless these bodies of water are shallow, the deep water below this layer is much colder (sometimes near 4jaC). The change in temperature between the warm surface water and the cold, deep water is called the thermocline. Mixing of the surface water by wave action determines the depth of the thermocline and maintains relatively constant temperatures in the water above it.

Tropical lakes and oceans show pronounced permanent stratification of their physical properties, with warm, well-oxygenated, and lighted surface water giving way to frigid, dark, deep water almost devoid of oxygen. Oxygen cannot be replenished at great depths where there are no photosynthetic organisms to produce it, and the stable thermal stratification prevents mixing and reoxygenation by surface water. Only relatively few organisms can live in such extreme conditions. The waste products and dead bodies of organisms living in the surface waters sink to the depths，taking their mineral nutrients with them. The lack of vertical circulation thus limits the supply of nutrients to the phytoplankton above. Consequently, deep tropical lakes are often relatively unproductive and depend on continued input from streams for the nutrients required to support life.

The situation is somewhat different in temperate and polar waters. Deep lakes，in particular, undergo dramatic seasonal changes: they develop warm surface temperatures and a pronounced thermocline in summer, but freeze over in winter. Twice each year, in spring and fall, the entire water column attains equal temperature and equal density; moderate winds may then generate waves that mix deep and shallow water，producing what is called overturn. This semiannual mixing carries oxygen downward and returns inorganic nutrients to the surface. Phosphorus and other nutrients may be depleted during the summer; overturn replenishes these nutrients by stimulating the growth of phytoplankton.

1. The word ultimately in the passage is closest in meaning to

a. probably

b. quickly

c. eventually

d. frequently

2. According to paragraph 2，which of the following is true about solar radiation

when it strikes water

a. Longer wavelengths travel farther.

b. Most of it is absorbed near the surface.

c. It is not absorbed by cloudy water.

d. More long wavelengths than short wavelengths are absorbed.

3. The word Virtually in the passage is closest in meaning to

a. Apparently

b. Usually

c. Nearly

d. Fortunately

4. According to paragraph 3，all of the following are true of kelp EXCEPT:

a. They are found at the bottom of shallow waters.

b. They are the primary producers of organic carbon.

c. They can grow very large.

d. They are a source of food for a variety of organisms.

5.The word suspended in the passage is closest in meaning to

a. dissolved

b. floating

c. invisible

d. released

6. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage Incorrect choices change the meaning in important ways or leave out essential information.

A. Zooplankton move up into surface waters at night to feed on phytoplankton, and down into deep, dark waters in daytime to avoid detection by predatory fish.

B. Zooplankton migrate vertically on a daily basis in order to feed on phytoplankton, following them up into surface waters by day and down into dark, deeper waters at night.

C. Unlike zooplankton, which migrate between surface waters and deeper waters, predatory fish must rely on the daytime light of surface waters to detect prey.

D. Zooplankton are so tiny that they can only be detected by predatory fish in the light conditions of surface water，where they feed on phytoplankton.

7. According to paragraph 4，what is a thermocline

a. The deep, cold layer of water below the surface of oceans and lakes

b. The thin layer of warm water on the surface of oceans and lakes

c. The change in density of surface water as it is continually heated

d. The point at which the temperature of water in oceans and lakes changes from warm to cold

8. The word replenished in the passage is closest in meaning to

a. absorbed

b. restored

c. contained

d. obtained

9. According to paragraph 5，all of the following are true of the water at great depths in tropical lakes EXCEPT:

a. It has less oxygen than the surface water does.

b. It is very dark.

c. It contains relatively few living organisms.

d. It has low levels of mineral nutrients.

10. The word dramatic in the passage is closest in meaning to

a. partial

b. complex

c. frequent

d. striking

11. According to paragraph 6，after overturn, deep water levels of lakes in temperate climates will contain increased amounts of

a. warm water

b. phosphorus

c. oxygen

d. phytoplankton

12. According to paragraphs 5 and 6，temperate lakes are in general more productive than tropical lakes because

a. temperate lakes receive more nutrients from incoming streams

b. the summer thermocline is relatively deep in temperate lakes

c. solar radiation penetrates more of the water in temperate lakes

d. temperate lakes experience vertical circulation of water

13. Look at the four squares that indicate where the following sentence could be added to the passage.

If the water is clouded by many microscopic organisms, absorption occurs even closer to the surface.

Where would the sentence best fit Click on a square to add the sentence to the passage.

14. Drag your choices to the spaces where they belong. To review the passage，click on View Text. Answer Choices

a. Sunlight is rapidly absorbed by the upper layer of water, which makes it warmer and consequently less dense than the water below.

B. Photosynthesizing plants, which provide the food and oxygen for most other forms of aquatic life, are limited to the levels of oceans and lakes where sunlight is available.

C. The diversity of plant life in shallow water makes it attractive to zooplankton.

D. As water becomes less dense and moves to the surface of the ocean or lake, it cools down and moderates the temperature of the surface.

E. Because more solar energy is absorbed by bodies of water in the tropics, the topmost layer of the thermocline is widest there.

F. In the tropics, permanent thermal stratification limits the amount of life supported in deep bodies of water; however, in temperate climates, seasonal thermal stratification allows vertical circulation and mixing of water, allowing the support of more life.

　　学科分类：古生物考古

　　题目：某恐龙是不是生活在水里

　　内容回忆：

第一段：一开始科学家猜测，某种恐龙因为体型很大，所以应该是生活在水里，用鼻子呼吸的。第二段：但是后来发现这种恐龙的腿很细，如果是牛活在水中的话，一定会长很大的脚掌才能够避免不陷进淤泥，所以这种恐龙可能生活在陆地上。第二段：将这种恐龙和大象进行比较。可能因为鼻子可以勾住树干以至于不会陷进泥潭，它们的结构和大象有相似之处。 第四段：因为这种恐龙四肢很适合跑步，所以可能是食肉的。而且它们体型能长到很大，相比哺乳动物来说，能够更好地控制体温。

　　词汇题：

immerse=extremely strong

extend延长，持续

以上就是2017年12月17日托福考试阅读真题的全部内容，内容为考生回忆，所以仅有文章概要。不过，从本次考试的主要内容中，考生依旧可以了解到近期托福考试阅读真题的话题。