引導語：本文為小編為大家帶來的語法解析之懸垂結構，希望對所有關注新SAT亞太首考動向的同學們有幫助。
新SAT考試中沿用了部分老SAT的語法考核點，其中modifier placement(修飾語)中懸垂結構的語病是很大的一個難點，尤其是涉及到None-finite verbs 非謂語動詞部分，是SAT考試最常考到的內容。要避免懸垂結構的語病，首先要明確，作伴隨狀語的非謂語動詞或介詞短語實際上可以理解為省略了和句子主幹相同的主語，如果邏輯上的主語和實際的主語不一致句子就會變得詞不達意。分清楚伴隨狀語的邏輯主語，確保其和句子的主語保持一致是關鍵。下面我們來具體分析。
首先，非謂語動詞包括現在分詞(doing)，過去分詞(done)，以及不定式(to do)三種形式。現在分詞doing一般表示動作伴隨著句子謂語的動作發生，和主語是主動關係;過去分詞done表示和主語的被動關係;而不定式to do一般表示目的性質。
如何避免懸垂結構的出現呢?就是要保證none-finite verbs的主語和句子主語一致，具體我們看下面的例子：
Visiting Paris two hundred years ago, the city would have looked very different.
A) NO CHANGE
B) Paris would have looked very different.
C) the difference in the city would be seen.
D) you would have seen a very different city.
這個句子中，Visiting Paris two hundred years ago是主幹部分的伴隨狀語，visiting的動作應當是由人發出，去拜訪兩百年之前的巴黎，人們會發現一個完全不同的city. 選項裡面只有D的you可以用作visiting的主語。
當伴隨狀語的結構用到過去分詞的時候也同理：
Based on the four years Behar spent interviewing Esperanza Hernández, a street peddler in the Mexican town of Mexquitic, Hernández felt torn between her Mexican and Indian identities.
A) NO CHANGE
B) the book recounts the tensions Hernandez felt
C) Behar found it fascinating that Hernandez felt torn
D) she recounts the tensions Hernandez felt
這個句子中Based on the four years B spent interviewing EH，指某事物是基於四年來B對EH的採訪，based的邏輯主語應當是某個事物或者觀點而不是人本身，所以選項裡面的the book可以作為based的主語，其他選項都會構成懸垂結構的語病。
伴隨狀語是介詞短語的情況下，同樣要注意主語一致性的問題：
Even with its shortcomings, the continued preservation of invaluable locales was made possible by the Antiquities Act of 1906.
A. )NO CHANGE
B. ) the Antiquities Act of 1906 made the continued preservation of invaluable locales possible.
C.) invaluable locales were saved from destruction and their continued preservation was made possible.
D.) the destruction of invaluable locales was prevented with the Antiquities Act of 1906, and it ensured continued preservation of such sites.
這個題目中with its shortcomings是with的介詞短語做伴隨，its這個物主代詞指代的是句中的Act，強調the Antiquities Act of 1906是存在不足的，preservation是並不完美的Act帶來的正向結果，因此用preservation做主語的選項都會構成懸垂結構的語病。