標點符號作為文章的有機組成部分，看起來微不足道，但往往就是這些不起眼的標點符號為我們提供了解題的線索。下面作者將介紹託福閱讀文章中幾個重要的標點符號，並結合實例來講解標點符號在託福閱讀中不容忽視的作用。
1. 託福閱讀中的冒號(colons)
冒號在中文或英文中都是一個常見的標點符號，在中英用法上也大致相同。冒號的主要作用有兩種：一是用在總說性話語或需要解釋的詞語後邊，引起下文的分說或引出解釋和說明;二是引出引語。在託福閱讀中，第一種用法對於我們理解文章和解題更加重要。例如：
① While the Greek world had expanded along the Mediterranean seas lanes, the Roman world was assembled by territorial conquest. Of course, the contrast is not quite so stark: in Alexander the Great the Greeks had found the greatest territorial conqueror of all time; and the Romans, once they moved outside Italy, did not fail to learn the lessons of sea power.
Why does the author mention 「Alexander the Great」 in the passage?
A. To acknowledge that Greek civilization also expanded by land conquest
B. To compare Greek leaders to Roman leaders
C. To give an example of Greek leader whom Romans studied
D. To indicate the superior organization of the Greek military
解析：這道修辭目的題出自TPO7Ancient Rome and Greece這篇文章，問為什麼提到Alexander the Great，修辭目的題的解題關鍵是弄清前後句子信息之間的邏輯關係。讀過原句之後，我們不難發現句中的冒號起著解釋說明的作用，其前面的「the contrast is not quite so stark」是個總說性句子，而後面的內容則是對總說句子的一個詳細解釋。這樣知道了冒號前後內容的聯繫之後，也就很容易解出這道目的題的答案A了。
又如：
② Four specific activities have been identified as major contributors to the desertification processes: overcultivation, overgrazing, firewood gathering, and overirrigation.
③ Now, other forms of life could take hold: ferns and mosses (two of the most ancient types of land plants) that flourish even in rock crevices.
解析：以上兩句話都是摘自TPO的文章，句中的冒號同樣是起著引起下文的分說的作用，分別舉例說明冒號前面總說詞語four specific activities 和other forms of life。
2. 託福閱讀中的破折號(dashes)
破折號在託福閱讀中也是尤為常見，其主要作用是引入一個解釋性的插入語，放在插入語的前面或者後面，破折號中的內容一般是對主句中的某個單詞或短語進行修飾或者解釋，作用相當於一個括號。考生就可以利用破折號之間的解釋來理解主句中的某個概念。例如：
① This unprecedented development of a finite groundwater resource with an almost negligible natural recharge rate—that is, virtually no natural water source to replenish the water supply—has caused water tables in the region to fall drastically.
The word 「virtually」 in the passage is closest in meaning to
A. Clearly
B. Perhaps
C. Frequently
D. Almost
解析：這是TPO 3 Depletion of the Ogallala Aquifer 中的一道詞彙題，單詞所在的原句中出現了兩個破折號，可以判斷破折號之間的是插入語，且插入語中出現了短語「that is」。根據破折號的用法，我們可知「that is」後面的內容是在解釋破折號前面的「an almost negligible natural recharge rate」。對於很多考生來說，「an almost negligible natural recharge rate」是個很抽象的概念，但是插入語中的信息就能夠幫助其理解這一概念的意思，繼而猜出virtually的意思，也就是D選項almost。
又如：
② Continued sedimentation—the process of deposits' settling on the sea bottom—buries the organic matter and subjects it to higher temperatures and pressures, which convert the organic matter to oil and gas.
③ From the Middle East the Chinese acquired a blue pigment—a purified form of cobalt oxide unobtainable at that time in China—that contained only a low level of manganese.
解析：在這兩句話中，破折號內部的信息是同樣是在進行解釋和說明，幫助我們理解sedimentation和pigment的這兩個詞的意思。
另外需要注意的一點是，插入語中的信息雖然能夠幫助考生理解破折號前面句子的意思，但是也很容易幹擾考生對句子主幹的把握。考生在遇到這樣的句子時，可以先忽略破折號之間的內容，直接看第二個破折號之後的內容。把握句子的主幹之後，再返回來看破折號內的插入語的內容。
3. 託福閱讀中的圓括號(parentheses)
英語中，圓括號最常見的用法是補充說明和解釋生詞，它們不同於逗號和破折號的用法，去掉後不會影響句子的理解，但是括號內的信息同樣對考生的理解有很大的幫助。例如：
① In the early twentieth century, however, it was discovered that much of the High Plains was underlain by a huge aquifer (a rock layer containing large quantities of groundwater).
② 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.
③ They sting other insects and large herbivores (animals that eat only plants) and even clip surrounding vegetation that grows near the tree.
解析：以上三句話中的括號都是在起補充說明的作用，很多考生不認識aquifer, Cretaceous以及herbivores這三個單詞，但是通過括號內的解釋就可以知其大致意思。
以上就是託福閱讀文章中三個比較重要的標點符號，這些標點符號往往會被考生忽略。但是，通過以上的分析可以看出，理解標點符號的用法不僅能夠幫助考生更好地理解文章，也有助於考生在做題過程中選出正確的答案，希望考生們能夠在平時練習時多注意標點符號的用法，並在託福考試中取得好成績!
(實習編輯：羅偉)