一個(gè)名詞(或其它形式)對另一個(gè)名詞或代詞進(jìn)行修飾，限定或說(shuō)明，這個(gè)名詞(或其它形式)就是同位語(yǔ)。當同位語(yǔ)部分是一個(gè)完整的句子時(shí)，它就是一個(gè)同位語(yǔ)從句。作為具有補充說(shuō)明和進(jìn)一步解釋功能的成分及名詞性從句之一，同位語(yǔ)及同位語(yǔ)從句在托福閱讀中出現的頻率是相當之高的。由于同位語(yǔ)及同位語(yǔ)從句表示與之同位的名詞的實(shí)際內容，因此它通常會(huì )大幅增加句子長(cháng)度，致使部分考生在閱讀過(guò)程中出現句意理解困難的問(wèn)題。因此，在平時(shí)的備考過(guò)程中，考生們應當注意將其作為一種長(cháng)難句結構進(jìn)行專(zhuān)門(mén)的練習。

　　一、同位語(yǔ)

　　同位語(yǔ)與被它限定的詞的格式一致，通常緊挨在一起，有時(shí)也會(huì )出現間隔現象。

　　1)In the seventeenth century the organ, the clavichord, and the harpsichord became the chief instruments of the keyboard group, a supremacy they maintained until the piano supplanted them at the end of the eighteenth century.

　　在此句中，the organ, the clavichord, and the harpsichord became the chief instruments of the keyboard group與a supremacy呈現同位語(yǔ)關(guān)系：

　　17世紀時(shí)風(fēng)琴、敲弦琴和撥弦琴成為鍵盤(pán)樂(lè )器類(lèi)的主要成員，這種至高無(wú)上的地位一直由它們保持，直到18世紀末被鋼琴所取代。

　　二、同位語(yǔ)從句

　　同位語(yǔ)從句是個(gè)完整的句子，它一般跟在某些名詞后面，用以說(shuō)明該名詞表示的具體內容。

　　2)Satire jars us out of complacence into a pleasantly shocked realization that many of the values we unquestioningly accept are false.

　　在此句中，many of the values we unquestioningly accept are false 為同位語(yǔ)從句，它由that引導，解釋了前面的名詞realization：

　　諷刺作品使我們擺脫了自滿(mǎn)情緒，并在愉快與震驚之中認識到：許多我們毫無(wú)疑問(wèn)地接受的價(jià)值觀(guān)是錯誤的。

　　注意：一般的“抽象”名詞都可以在之后跟同位語(yǔ)從句，例如：reminder(提醒)， realization(了解)，skepticism(懷疑)，argument(爭論)，rumor(謠言)，prospect(預期)，evidence(證據)，boast that(引以為豪的事)， claim (宣稱(chēng))，words(消息)等：

　　3)There are numerous unsubstantiated reports that natural vitamins are superior to synthetic ones, that fertilized eggs are nutritionally superior to unfertilized eggs, that untreated grains are better than fumigated grains and the like.

　　在此句中，natural vitamins are superior to synthetic ones, fertilized eggs are nutritionally superior to unfertilized eggs, untreated grains are better than fumigated grains and the like 三個(gè)同位語(yǔ)從句均由that引導，補充說(shuō)明前面的名詞reports。

　　關(guān)于天然維生素優(yōu)于人造維生素，受精蛋比未受精蛋的營(yíng)養價(jià)值更高，未經(jīng)熏蒸消毒處理的谷物比經(jīng)過(guò)處理的好等等報道屢見(jiàn)不鮮，但都沒(méi)有得到證實(shí)。

　　4)It has lived because readers appreciate a refreshing stimulus, an irreverent reminder that they lived in a world of platitudinous thinking, cheap moralizing, and foolish philosophy.

　　在此句中，a refreshing stimulus與an irreverent reminder呈現同位語(yǔ)關(guān)系，而they lived in a world of platitudinous thinking, cheap moralizing, and foolish philosophy亦為同位語(yǔ)從句，由that引導，補充說(shuō)明了前面的名字reminder：

　　它之所以存在，是因為讀者欣賞它使人耳目一新的刺激，它毫不客氣地提醒：他們活在一個(gè)充滿(mǎn)陳腐思想、廉價(jià)的道德說(shuō)教與荒謬哲學(xué)的世界里。

　　練習：

　　1.As a result, claims that eating a diet consisting entirely of organically grown foods prevents or cures disease or provides other benefits to health have become widely publicized and form the basis for folklore.

　　2.The argument that humans，even in prehistoric times，had some number sense，at least to the extent of recognizing the concepts of more and less when some objects were added to or taken away from a small group, seems fair, for studies have shown that some animals possess such a sense.

　　3. Keen observers and quick learners, crows are astute about the intentions of other creatures, including researchers, and adept at avoiding them.