托福閱讀主旨題題型都有哪些呢？

相比較於國內的英語閱讀考試，托福閱讀不僅文章篇幅較長，句式豐富，辭彙較為學術，閱讀的題型更是五花八門。同學們很難判斷究竟是先看文章還是先看題目，同學們也有諸如，做題前，是否要看每個段落的首末句？做題的基本步驟？兩步？三步？做題前是否要優先花費時間通讀全文？此類的新手入門問題，本文通過十大題型給同學們做出詳細的回答。

為了回答好這些問題，同學們首先要了解托福閱讀考試的題型大致可分為三大類，基礎理解，推理，以及總結。當然，每一大類又可細分為具體的題型，以此類推，又可細化出10大類。具體分類如下：

基礎理解類

1. 事實信息

2. 否定信息

3. 句子簡化

4. 指代

5. 辭彙

推理類

6. 推理題

7. 目的題

8. 插入題

總結類

9. 文章總結題

10. 表格分類題

不同類型的題目，對於同學們技能的考察也不相同。基礎理解類的題目強調同學們的同義替換，總結，掃讀及語法的能力。而對於推理類的題目，則更多得考察同學們對文章段落結構的把握以及推論的能力。總結類題型則強調對文章段落的總結和具體知識點的考察。因此，對於不同的題型，在回答的技巧和策略上也需要進行調整。

就三大類而言，題目的難度由低到高，總結類的題目可以說難度最高，基礎理解類最低，也是佔比較高的題型。所以，如果同學能夠提高基礎理解類題型準確率，能夠很大程度上提高自己的整體閱讀成績。畢竟，這一大類的題型佔到考試比重的80%左右。

Type 1 事實信息題

這個類別的題型和否定信息題加在一起可以幾乎達到考試整體的百分之四十。也就是說一篇文章12-14道題可以有4題左右的事實信息和否定信息類的題目。這類題目的解答通常並不需要閱讀完整篇文章或段落，而僅僅需要某一句話，精準的定位能力是回答此類問題的關鍵。 此類題目多以true來詢問，以下題為例：

P1.Paleontologists have argued for a long time that the demise of the dinosaurs was caused by climatic alterations associated with slow changes in the positions of continents and seas resulting from plate tectonics. Off and on throughout the Cretaceous (the last period of the Mesozoic era, during which dinosaurs flourished), large shallow seas covered extensive areas of the continents. Data from diverse sources, including geochemical evidence preserved in seafloor sediments, indicate that the Late Cretaceous climate was milder than today』s. The days were not too hot, nor the nights too cold. The summers were not too warm, nor the winters too frigid. The shallow seas on the continents probably buffered the temperature of the nearby air, keeping it relatively constant.

Q1.According to paragraph 1, which of the following is true of the Late Cretaceous climate?

A. Summers were very warm and winters were very cold.

B. Shallow seas on the continents caused frequent temperature changes.

C. The climate was very similar to today』s climate.

D. The climate did not change dramatically from season to season

以上是一道典型的托福閱讀的細節題型，雖然是給出整段，但是同學們不需要通讀整段。同學們可以根據題目的關鍵字，即the Late Cretaceous climate到文章段落中去定位。同學們可以發現在段落的倒數第四句可以找到這個單詞，並且也提到了和當今的氣候的一個對比。在倒數第四句附近進行精讀，同學們不難發現，其後一句也就是倒數第三句，說到夏天不是很熱，冬天也不是很涼。最後一句，說大陸架上的淺海使得溫度相對穩定。從這兩個關鍵句上，我們不難得出答案就是選項Ｄ，因為這裡提到了季節變化不劇烈這個意思。因此，這道題並不用通讀文章段落就可以得出正確的答案。同學們可以看出，此題所考察的主要能力包括定位以及同義替換。這兩種能力對於基礎題型的解答都比較重要。當然，事實信息題也會詢問一些與文章事實相關的內容，例如，According to the paragraph, why did X do Y? 就答題技巧上而言，和詢問true類型的題目答題步驟相同。

Type 2 否定信息題

此類題目的一大特徵就是，題干中有NOT true 和EXCEPT詢問是會要求考生先將包含正確信息的選項排除，所以可以看成事實信息題的對立題型，在答題技巧上也並沒特別，與事實信息題相似。以下題為例：

P2. The Ogallala aquifer is a sandstone formation that underlies some 583,000 square kilometers of land extending from northwestern Texas to southern South Dakota. Water from rains and melting snows has been accumulating in the Ogallala for the past 30,000 years. Estimates indicate that the aquifer contains enough water to fill Lake Huron, but unfortunately, under the semiarid climatic conditions that presently exist in the region, rates of addition to the aquifer are minimal, amounting to about half a centimeter a year.

Q2.According to paragraph 2, all of the following statements about the Ogallala aquifer are true EXCEPT:

A. The aquifer stretches from South Dakota to Texas.

B. The aquifer』s water comes from underground springs.

C. Water has been gathering in the aquifer for 30,000 years.

D. The aquifer』s water is stored in a layer of sandstone.

對於這道題，同學們可以選取題目中的Ogallala aquifer直接定位到段落的開頭，通過段落的前兩句把問題的答案篩選出來。選項A和D都在第一句中，而選項B和C都在第二句中。選項B的與第二句中from rains and melting snows信息相反，而其它選項都正確，所以B是正確的答案。通過這道題，同學可以注意到該段落的後半部分完全不需要去進行閱讀。答案都在定位詞的附近。此題所考察的主要能力也是定位以及同義替換，比如選項A的同義表達。

Type 3 句子簡化

句子簡化題型可以說是托福閱讀考試中最具代表性的題型之一，可以說在其它海外留學語言考試中都沒有類似的題型。此類題型通常都是選取非常複雜的句子，要求考生選取出能夠同義替換或者表述相同內容的信息。此類題型主要是考察考生的精讀能力。通過找准句子的各個結構，從而確定長句子的準確意思。具體例題如下：

P5.An even more exciting find was reported in 1994, also from Pakistan. The now extinct whale Ambulocetus natans ("the walking whale that swam") lived in the Tethys Sea 49 million years ago. It lived around 3 million years after Pakicetus but 9 million before Basilosaurus. The fossil luckily includes a good portion of the hind legs. The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea. The whale retained a tail and lacked a fluke, the major means of locomotion in modern cetaceans. The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing. The large hind legs were used for propulsion in water. On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion. It was undoubtedly a whale that linked life on land with life at sea

Q3.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. Even though Ambulocetus swam by moving its body up and down, it did not have a backbone.

B. The backbone of Ambulocetus, which allowed it to swim, provides evidence of its missing fluke.

C. Although Ambulocetus had no fluke, its backbone structure shows that it swam like modern whales.

D. By moving the rear parts of their bodies up and down, modern whales swim in a different way from the way Ambulocetus swam.

對於這道題，通過對於語法的分析，可以得出，所劃的句子是賓語從句，強調的主要意思就是shows後面的從句，however的位置應當提前，所以這個只要搞清楚賓語從句的主要內容，也就能夠把握住該句的主要核心信息，即儘管fluke不存在,但是Ambulocetus通過上下擺動其後半部分，游起來類似現代鯨魚。因此，可以判斷出選項C的核心信息與所劃句子的信息吻合。 為了答好這類題目，同學應該具備能夠分析句子結構的能力，掌握常見的邏輯關係，把握句子的核心信息，相比較前兩種題型，此類題型也是進行同義替換，但更加強調整個句子的同義替換。

Type 4 指代

應該算是最沒有難度的題型，沒有之一。基本上，大部分的同學通過對於單詞的位置都能夠推出該詞所指的對象。主要技巧在於，如果代詞在句首，那麼就在前一句中看其主句的主語，而如果代詞在句中，需要找到本句中的主語。儘管該種題型的比例較少，甚至可以說並非必考題型，但依然可以當作一種單獨的題型。具體例題如下：

P3.The fossil consists of a complete skull of an archaeocyte, an extinct group of ancestors of modern cetaceans. Although limited to a skull, the Pakicetus fossil provides precious details on the origins of cetaceans. The skull is cetacean-like but its jawbones lack the enlarged space that is filled with fat or oil and used for receiving underwater sound in modern whales. Pakicetus probably detected sound through the ear opening as in land mammals. The skull also lacks a blowhole, another cetacean adaptation for diving. Other features, however, show experts that Pakicetus is a transitional form between a group of extinct flesh-eating mammals, the mesonychids, and cetaceans. It has been suggested that Pakicetus fed on fish in shallow water and was not yet adapted for life in the open ocean. It probably bred and gave birth on land.

Q4.The word 「It」 in the passage refers to

A. Pakicetus

B. fish

C. life

D. ocean

對於該類型的題目，只要通過後面的具體內容bred and gave birth on land就不難得出，它所指代得是種生物，再往前，可以看到Pakicetus是種生物，而通過fed on fish可以得出這種生物依靠fish為生，因此答案只可能是A。事實上，對於這種題型，同學們也可以使用排除法把選項往其中進行代入，就可以比較容易得出答案。

Type 5 辭彙

相比較剛才的指代題，辭彙題的難度可以說既簡單又困難，而且其考察數量基本每篇文章都能達到兩篇，數量龐大。如果同學能夠認識該單詞那麼很快就能夠選出正確答案，但是如果不能認識單詞，再去文章中看語義背景環境，再去猜該單詞的意思，那麼就會耗時又耗力。因此，對於單詞的積累，也是同學們在準備托福閱讀考試的必修課之一。以下是一道例題：

P6. Ecologists are especially interested to know what factors contribute to the resilience of communities because climax communities all over the world are being severely damaged or destroyed by human activities. The destruction caused by the volcanic explosion of Mount St. Helens, in the northwestern United States, for example, pales in comparison to the destruction caused by humans. We need to know what aspects of a community are most important to the community』s resistance to destruction, as well as its recovery.

Q5. The word 「pales」 in the passage is closest in meaning to

A. increases proportionally

B. differs

C. loses significance

D. is common

pale這個單詞對於很多認識這個單詞的同學來說是個形容詞，指的是蒼白的，但是這裡加上s變成pales,因此，在這裡使用其動詞的意思，變得蒼白，如果同學已經知道這個意思就不會有太大的難度選擇出正確答案C。但是，如果同學們並不清楚該單詞的意思，那麼就只能從文章的語義中來判斷，比如，該句中有destruction這個負面項的辭彙，因此，在推測其語義的時候，可以更多的考慮消極方面的同義替換，因此在四個選項中，A 表成比例地增加 B表不同於 D表相同，只有C 表失去重要性，因此，從文章傾向性上推測也只能夠選擇C。雖然，這樣推測的方法也會選出正確的選項，但是，比較耗時，因此，還是強烈建議同學們掌握大量單詞，這樣再回答該類型問題時，才能高效地回答。

Type 6 推理題

相對於前面幾種題型，該題型在對於文章理解上的要求偏高，要求考生對於文章語句有一定程度上理解。換句話說也就是選出使用不同辭彙和語法結構但是卻表述相同意思的選項。該類型題目的標誌性單詞是infer和imply。具體出題問法通常都是」Which of the following can be inferred about X?」 」The author of the passage implies that X …」

具體例題如下：

P5.Two other developments presaged the end of the era of turnpikes and started a transportation revolution that resulted in increased regional specialization and the growth of a national market economy. First came the steamboat; although flatboats and keelboats continued to be important until the 1850』s steamboats eventually superseded all other craft in the carrying of passengers and freight. Steamboats were not only faster but also transported upriver freight for about one tenth of what it had previously cost on hand-propelled keelboats. Next came the Erie Canal, an enormous project in its day, spanning about 350 miles. After the canal went into operation, the cost per mile of transporting a ton of freight from Buffalo to New York City declined from nearly 20 cents to less than 1 cent. Eventually, the western states diverted much of their produce from the rivers to the Erie Canal, a shorter route to eastern markets.

Which of the following can be inferred from paragraph 5 about flatboats and keelboats?

A. They ceased to be used as soon as the first turnpikes were built.

B. They were slower and more expensive to operate than steamboats.

C. They were used for long-distance but not for regional transportation.

D. They were used primarily on the Erie Canal.

對於這樣類型的題目很明顯，同學們首先會去讀文章，然後看題，之後可能再去看文章段落，因此，這樣很有可能費時費力，對於這道題，同學們可以通過題干里的flatboats and keelboats作為定位詞，同學們可以直接從第二個句子although開始看起。正確的答案就是從although flatboats and keelboats continued to be important until the 1850』s steamboats eventually superseded all other craft in the carrying of passengers and freight. Steamboats were not only faster but also transported upriver freight for about one tenth of what it had previously cost on hand-propelled keelboats.這兩句話判斷出，只要同學能夠正確理解這兩句話的意思，那麼正確答案也就能夠出來。那麼下面我們把這兩句話翻譯一下：儘管flatboats 和keelboats 持續扮演著重要的角色，直到19世紀50年代，steamboats最終替代其他船隻運送旅客和貨物。Steamboats不僅在河上游開得更快，並且其成本也只需要以前人力驅動keelboats的十分之一。

雖然翻譯的部分只有兩個句子並且並沒有直接提及flatboats 和keelboats如何如何，但是通過第二句話，我們可以比較清楚地推出其他兩種船不僅速度沒有steamboats快，成本可能也比較高。根據這個意思，我們可以很容易地選出正確的答案是選項B。如果同學把其他部分都看懂，但是就是沒有找到這句話，是不能選出正確的選項得。因此，準確地定位和合完整的理解是答好此類題型的關鍵。

Type 7 目的題

和推理題類似，同學們也要對文章的內容有一定的理解，這類題目大多考察對於段落的理解，比如前後的關係，或者作者的意圖。和推理題有很大的類似性。這類題目的典型文法就是why 和purpose

具體題目如下：

P3. The first wells were drilled into the Ogallala during the drought years of the early 1930s. The ensuing rapid expansion of irrigation agriculture, especially from the 1950s onward, transformed the economy of the region. More than 100,000 wells now tap the Ogallala. Modern irrigation devices, each capable of spraying 4.5 million liters of water a day, have produced a landscape dominated by geometric patterns of circular green islands of crops. Ogallala water has enabled the High Plains region to supply significant amounts of the cotton, sorghum, wheat, and corn grown in the United States. In addition, 40 percent of American grain-fed beef cattle are fattened here.

In paragraph 3, why does the author provide the information that 40 percent of American cattle are fattened in the High Plains?

A To suggest that crop cultivation is not the most important part of the economy of the High Plains

B To indicate that not all economic activity in the High Plains is dependent on irrigation

C To provide another example of how water from the Ogallala has transformed the economy of the High Plains

D To contrast cattle-fattening practices in the High Plains with those used in other region of the United States

這道題和推理題比較類似，同學們可以很清楚地看到題目問及40 percent of American cattle are fattened in the High Plains這句話就位於該段落的最後一句，因此，既然題目問為什麼，那麼就往前看，in addition是並列關係的表達，因此40 percent of American cattle are fattened in the High Plains和前面的句子Ogallala water has enabled the High Plains region to supply significant amounts of the cotton, sorghum, wheat, and corn grown in the United States呈現並列關係，而這個句子的意思主要是Ogallala的水養活在High plains地區的大量棉花，高粱，小麥和玉米。因此根據這個意思，四個選項中，唯一相關的就只有選項C。選項D的錯誤在於文章沒有對比，選項B的錯誤在於文章沒有設計灌溉。雖然文章有提到現代灌溉工具，但和考察內容並不有直接關係。選項A則是毫無根據。只有選項C可以another example 可以將In addition 前面的句子看成一個example,而40% 則是另一個example 因此，完全正確。

通過這道題，同學們應該能夠比較清楚地了解，雖然能夠很好的定位，但是句子和句子的邏輯關係以及句子本身所表述的意思都是選出正確選項重要的內容。

Type 8 插入題

如果說目的題有考察到同學們對段落句子的邏輯考察，那麼插入題對邏輯關係的考察則更加的密切。題目的典型考察方法就是給出一個句子，問同學插入在四個點當中，哪個比較合適。此類題型，相較而言，並不算十分困難，從給出的句子中理解基本意思，然後在文章中，尋找什麼地方可以插入該意思。具體題型如下:

Q8.Look at the four squares [█] that indicate where the following sentence could be added to the passage.

However, these animals have additional means of staying warm.

Where would the sentence best fit?

P3.Leatherbacks keep their body heat in three different ways. The first, and simplest, is size. The bigger the animal is, the lower its surface-to-volume ratio; for every ounce of body mass, there is proportionately less surface through which heat can escape. An adult leatherback is twice the size of the biggest cheloniid sea turtles and will therefore take longer to cool off. Maintaining a high body temperature through sheer bulk is called gigantothermy. █ It works for elephants, for whales, and, perhaps, it worked for many of the larger dinosaurs. █It apparently works, in a smaller way, for some other sea turtles. █Large loggerhead and green turtles can maintain their body temperature at a degree or two above that of the surrounding water, and gigantothermy is probably the way they do it. █Muscular activity helps, too, and an actively swimming green turtle may be 7°C (12.6°F) warmer than the waters it swims through.

對於這道題，同學們可以很清楚在首句看到這個段落都是在講保溫的方法。那麼再看句子的內容是有額外的保溫的方法additional means of staying warm.，那麼這個句子最佳的插入點應該是文中已經有提到過保溫的內容之後，按照這樣的語義，我們可以看到在首句之後，the first後面開始解釋和說明第一種保溫的方法，而無論是第一個點和第三點都是在解釋說明第一種保溫方法，也就是所謂的gigantothermy的方法，而最後一個點的內容則是說到另一種保溫方法，因此，合適的插入點就是最後一個。所以，通過句中簡單的邏輯並列關係和句義內容，同學們就能夠很快找到準確的答案。抓住邏輯關係和語義內容，也就能很好的選擇正確的內容。

Type 9 文章總結題

最後兩種題型，文章總結題和完成表格都是總結類型的題目，他們都是位於考試中的最後一道題，並且不會同時出現。相比較於前面的其他八種題型，這兩種類型的題目的分值也較高。當然，這兩種題目的錯誤率普通來說也較高，通常的原因是位於最後，同學們基本上沒有更多得時間，所以多數同學在做最後一題的時候可能保佑僥倖心理，隨便選答案。但兩種題型在出題方式上還是有著巨大的差異。文章總結題具體例題如下：

Q9.

Direction：

An introductory sentence or a brief summary of the passage is provided below. Complete the summary by selecting the three answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

The process of succession and the stability of a climax community can change over time.

●

●

●

Answer choices：

A. The changes that occur in an ecosystem from the pioneer to the climax community can be seen in one human generation.

B. A high degree of species diversity does not always result in a stable ecosystem.

C. The level of resilience in a plant community contributes to its long-term stability.

D. Ecologists agree that climax communities are the most stable types of ecosystems.

E. Disagreements over the meaning of the term 「stability」 make it difficult to identify the most stable ecosystems.

F. The resilience of climax communities makes them resistant to destruction caused by humans.

The Long-Term Stability of Ecosystems

P1.Plant communities assemble themselves flexibly, and their particular structure depends on the specific history of the area. Ecologists use the term 「succession」 to refer to the changes that happen in plant communities and ecosystems over time. The first community in a succession is called a pioneer community, while the long-lived community at the end of succession is called a climax community. Pioneer and successional plant communities are said to change over periods from 1 to 500 years. These changes—in plant numbers and the mix of species—are cumulative. Climax communities themselves change but over periods of time greater than about 500 years.

P2.An ecologist who studies a pond today may well find it relatively unchanged in a year』s time. Individual fish may be replaced, but the number of fish will tend to be the same from one year to the next. We can say that the properties of an ecosystem are more stable than the individual organisms that compose the ecosystem.

P3.At one time, ecologists believed that species diversity made ecosystems stable. They believed that the greater the diversity the more stable the ecosystem. Support for this idea came from the observation that long-lasting climax communities usually have more complex food webs and more species diversity than pioneer communities. Ecologists concluded that the apparent stability of climax ecosystems depended on their complexity. To take an extreme example, farmlands dominated by a single crop are so unstable that one year of bad weather or the invasion of a single pest can destroy the entire crop. In contrast, a complex climax community, such as a temperate forest, will tolerate considerable damage from weather to pests.

P4.The question of ecosystem stability is complicated, however. The first problem is that ecologists do not all agree what 「stability」 means. Stability can be defined as simply lack of change. In that case, the climax community would be considered the most stable, since, by definition, it changes the least over time. Alternatively, stability can be defined as the speed with which an ecosystem returns to a particular form following a major disturbance, such as a fire. This kind of stability is also called resilience. In that case, climax communities would be the most fragile and the least stable, since they can require hundreds of years to return to the climax state.

P5.Even the kind of stability defined as simple lack of change is not always associated with maximum diversity. At least in temperate zones, maximum diversity is often found in mid-successional stages, not in the climax community. Once a redwood forest matures, for example, the kinds of species and the number of individuals growing on the forest floor are reduced. In general, diversity, by itself, does not ensure stability. Mathematical models of ecosystems likewise suggest that diversity does not guarantee ecosystem stability—just the opposite, in fact. A more complicated system is, in general, more likely than a simple system to break down. A fifteen-speed racing bicycle is more likely to break down than a child』s tricycle.

P6.Ecologists are especially interested to know what factors contribute to the resilience of communities because climax communities all over the world are being severely damaged or destroyed by human activities. The destruction caused by the volcanic explosion of Mount St. Helens, in the northwestern United States, for example, pales in comparison to the destruction caused by humans. We need to know what aspects of a community are most important to the community』s resistance to destruction, as well as its recovery.

P7.Many ecologists now think that the relative long-term stability of climax communities comes not from diversity but from the 「patchiness」 of the environment, an environment that varies from place to place supports more kinds of organisms than an environment that is uniform. A local population that goes extinct is quickly replaced by immigrants from an adjacent community. Even if the new population is of a different species, it can approximately fill the niche vacated by the extinct population and keep the food web intact.

通過閱讀整篇文章，同學們可以發現選項A原文章第一段的最後一句意思相反，因此不選。選項B對應原文第三段和第五段以及第四段的大意，正確，選。選項C對應原文第六段，第四段的大意，正確，選。選項D與原文第三段第四段首句意思相反，不選。選項E，對應原文第四段大意，正確，因此，選。選項F，原文並沒有提及，不選。因此正確的選項為BCE。

同學們可以發現這樣的題目放在最後正好是為了方便同學們把文章整體了解以後進行答題，事實上，儘管此類題型偏重整體文章，但同學們對於具體選項的回答也無法擺脫段落中的細節，因此加強對於細節的把握亦是答好此種題型的關鍵。

Type 10表格分類題

和前面的題型一樣，偏重於考察全篇。但是對於文章的具體內容有所細化。

Q10.

Directions: Select from the seven sentences below, the two sentences that correctly characterize endogenous rivers and the three sentences that correctly characterize exogenous rivers. Drag each sentences you select into the appropriate column of the table. Two of the sentences will NOT be used. This question is worth 3 points.

Endogenous Rivers

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Exogenous Rivers

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Answer Choices

A. Their water generally comes from groundwater springs.

B. Their water is saltier than the water of most other rivers.

C. They include some of the world"s largest rivers.

D. They originate outside the desert.

E. They often drain into inland basins and do not reach the sea.

F. They contain too much silt to be useful for irrigation

G. Their water flow generally varies with the season of the year.

Water in the Desert

P1.Rainfall is not completely absent in desert areas, but it is highly variable. An annual rainfall of four inches is often used to define the limits of a desert. The impact of rainfall upon the surface water and groundwater resources of the desert is greatly influenced by landforms. Flats and depressions where water can collect are common features, but they make up only a small part of the landscape.

P2.Arid lands, surprisingly, contain some of the world』s largest river systems, such as the Murray-Darling in Australia, the Rio Grande in North America, the Indus in Asia, and the Nile in Africa. These rivers and river systems are known as "exogenous" because their sources lie outside the arid zone. They are vital for sustaining life in some of the driest parts of the world. For centuries, the annual floods of the Nile. Tigris, and Euphrates, for example, has brought fertile silts and water to the inhabitants of their lower valleys. Today, river discharges are increasingly controlled by human intervention, creating a need for international river-basin agreements. The filling of the Ataturk and other dams in Turkey has drastically reduced flows in the Euphrates, with potentially serious consequences for Syria and Iraq.

P3.The flow of exogenous rivers varies with the season. The desert sections of long rivers respond several months after rain has fallen outside the desert, so that peak flows may be in the dry season. This is useful for irrigation, but the high temperatures, low humidity, and different day lengths of the dry season, compared to the normal growing season, can present difficulties with some crops.

P4.Regularly flowing rivers and streams that originate within arid lands are known as "endogenous." These are generally fed by groundwater springs, and many issue from limestone massifs, such as the Atlas Mountains in Morocco. Basaltic rocks also support springs, notably at the Jabal Al-Arab on the Jordan-Syria border. Endogenous Rivers often do not reach the sea but drain into inland basins, where the water evaporates or is lost in the ground. Most desert streambeds are normally dry, but they occasionally receive large flows of water and sediment.

P5.Deserts contains large amounts of groundwater when compared to the amounts they hold in surface stores such as lakes and rivers. But only a small fraction of groundwater enters the hydrological cycle-feeding the flows of streams, maintaining lake levels, and being recharged (or refilled) through surface flows and rainwater. In recent years, groundwater has become an increasingly important source of freshwater for desert dwellers. The United Nations Environment Program me and the World Bank have funded attempts to survey the groundwater resources of arid lands and to develop appropriate extraction techniques. Such programs are much needed because in many arid lands there is only a vague idea of the extent of groundwater resources. It is known, however, that the distribution of groundwater is uneven, and that much of it lies at great depths.

P6.Groundwater is stored in the pore spaces and joints of rocks and unconsolidated (unsolidified) sediments or in the openings widened through fractures and weathering. The water-saturated rock or sediment is known as an "aquifer". Because they are porous, sedimentary rocks, such as sandstones and conglomerates, are important potential sources of groundwater. Large quantities of water may also be stored in lime stones when joints and cracks have been enlarged to form cavities. Most limestone and sandstone aquifers are deep and extensive but may contain ground waters that are not being recharged. Most shallow aquifers in sand and gravel deposits produce lower yields, but they can be rapidly recharged. Some deep aquifers are known as "fossil waters. The term "fossil" describes water that has been present for several thousand years. These aquifers became saturated more than 10,000 years ago and are no longer being recharged.

P7.Water does not remain immobile in an aquifer but can seep out at springs or leak into other aquifers. The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) ground waters has still not reached equilibrium after 70 years of being tapped. The mineral content of groundwater normally increases with the depth, but even quite shallow aquifers can be highly saline.

在文章中，同學們可以發現第二段第二句說到exogenous，第四段說到endogenous。那麼第二段第一句說到最大的河流，對應選項C 的they include選項；而這段的第二句說這些河流源自乾旱區之外，對應選項D的they originate的內容；第三段的開頭對應選項G 里their water flow的內容；因此，CDG這三個是exogenous的答案；第四段的第二句和第四句分別對應選項A 里their water generally的 內容和選項E里they often的內容，AE這兩個是endogenous的答案。