1. 即使是因為意思上的需要而使得我們只能選擇某一句作為從屬子句，我們依舊有選擇從屬連詞的機會：
Michelangelo’s Pieta was damaged by a madman recently.
Michelangelo’s Pieta is now displayed only behind a protective glass shield.
Because/ Since/ After Michelangelo’s Pieta was damaged by a madman recently, it is now displayed only behind a protective glass shield.
OR
Because/ Since/ After it was damaged by a madman recently, Michelangelo’s Pieta is now displayed only behind a protective glass shield.
這里的because和since表原因，after表時間。
請學習下面例句中各種形式含義的從屬子句：
例句：
Air traffic is closely controlled.
Flying is relatively safe/unsafe.
CONDITION: IF/ Provided that/ In case/ Assuming that/ Imaging that/ Supposing that air traffic is closely controlled, flying is relatively safe.
DEGREE: Inasmuch as/ Insofar as/ To the extent that air traffic is closely controlled, flying is relatively safe.
REASON:Because/ Since/ Considering that air traffic is closely controlled, flying is relatively safe.
TIME: When/ Whenever/ As long as/ While/ Once air traffic is closely controlled, flying is relatively safe.
PLACE: Where/ Wherever air traffic is closely controlled, flying is relatively safe.
OR
CONDITION: Unless air traffic is closely controlled, flying is relatively unsafe.
(negative)
CONTRAST: Although/ Even though air traffic is closely controlled, flying is relatively unsafe.
CONDITION: Whether or not air traffic is closely controlled, flying is relatively unsafe.
(alternative)
2. 另一方面，當介詞短語修飾的是一個較短的主語，那么該短語可以出現在該名詞的任意一邊，請看下例：
Calder’s art has exuberant simplicity.
Calder’s art represents a complex fusion of many elements.
↓
For all its exuberant simplicity, Calder’s art represents a complex fusion of many elements.
OR
Calder’s art,for all its exuberant simplicity, represents a complex fusion of many elements.
3. 兩句謂語結構類似的句子要合并的話，其中一個往往會使用到介詞——通常有after, aside from, before, besides, by, for, in,或者without——后面緊跟現在分詞ING形式：
Virginia Woolf wrote a lovely suicide note to her husband.
Then she drowned herself.
↓
Before drowning herself, Virginia Woolf wrote a lovely suicide note to her husband.
OR
Virginia Woolf, before drowning herself, wrote a lovely suicide note to her husband.
介詞with有時被用來引導獨立主格：
We crossed the river by ferry.
The bus accompanied us.
↓
We crossed the river by ferry, with the bus accompanying us.
4. 介詞短語可以被用來構造平行結構，無論是通過配對的介詞或是同一個介詞一系列的重復，都是可行的。使用配對介詞比如from-to, with-without, for-against可以起到相反事物的平衡作用：
The mad dancing epidemics of southern Europe in the Middle Ages have been blamed on everything from mildew in the rye meal to religious fanaticism.
而一系列的同一介詞的使用，可以用來列舉平行的觀點：
The Chinese have built a society with an educational system radically different from ours, with aspirations challenging some of our most cherished values, and with a strong sense of mission at times enviable, at times frightening.
5. 外表與介詞短語相似的是副詞不定式。這些不定式通常由介詞to 或in order to引導，后面跟隨的對象是動詞原形： to see, to write, to daydream副詞不定式通常表示一個目的，目標或是決心，是某人“想”做的一件事：
Your purpose is becoming a liberated woman.
You don’t have to act as a man is supposed to act, according to outdated stereotypes.
↓
To become a liberated woman, you don’t have to act as a man is supposed to act, according to outdated stereotypes
通常情況下，不定式被默認為和句子的其他成分有著同一個主語，特別是不定式較短的時候。但這一規則經常被忽略，尤其是使用了通用的習慣用法，比如：to be sure, to tell you the truth, to put it differently, to begin with, to give an example:
I want to tell you the truth.
Melvin is incompetent.
To tell you the truth, Melvin is incompetent.
不定式做狀語既可以在句子的末尾也可以放在句子的開頭：
Medical students serve an internship in order to gain first-hand experience before they officially enter into a medical career.
它們也可以放在句子中間，前后用逗號隔開，表插入語：
Repeaters are given study materials designed especially for them, and, to avoid the stigma of studying with younger children, placed in classes with children their own age.
有時一個插入的不定式通過迫使讀者在它們之前停頓一下而達到特殊的強調效果。但該用法通常是在文學中使用，只作為欣賞，不建議大家使用：
Man is, to use the author’s own term, a superprimate.
不定式也能多個出現，既可在主句之前，也可在主句之后。在多個出現的不定式短語中，除第一個to之外，其他的都被省略了：
To meet our energy needs, compete with foreign industry, build a projected 30 million new homes, and maintain our standard of living, we need staggering amounts of new capital.
最后一個例子說明了不定式做狀語比用其他方法更為簡潔和雅致的優點：
The Reverend Elisabeth Jans wants to erase the traditional image of God as a man.
The Reverend Elisabeth Jans refers to God as a woman.
↓
Because she wants to erase the traditional image of God as a man, the Reverend Elisabeth Jans refers to God as a woman.
OR
To erase the traditional image of God as a man, the Reverend Elisabeth Jans refers to God as a woman
但請注意和獨立主格連在一起的逗號，或者象是破折號一類的是不能被刪除的。還有，邏輯關系也是值得注意的，時間先后順序不能顛倒哦。
總的來說，獨立主格在句子的當中或是末尾的效果最好，但是，如果要表示原因或者結果的話就一定要放在句子的開頭才有效果。
6. 與分詞短語和同位語一樣，獨立主格也可以連續使用，為渲染氣氛制造強有力的效果：
The arrested woman was slammed against a wall, her body frisked, her wrists handcuffed, her dignity lost.
當我們所要代替的名詞是專有名詞（某人的名字或某物的名稱）時，必須在這前后加上逗號：
Paul McCartney has been more successful than the other ex-Beatles.
Paul McCartney is the founder of Wings.
↓
Paul McCartney, who is the founder of Wings, has been more successful than the other ex-Beatles.
在上面的例子中，關系從句通過增加細節來修飾名詞。而細節則能使作品更生動有力。
關系從句通常可以被簡化成其他更緊湊或是更有效的結構：
Jupiter has 11 moons.
Jupiter is the largest planet in the solar system.
↓
Jupiter, which is the largest planet in the solar system, has 11 moons.
OR
Jupiter, the largest planet in the solar system, has 11 moons.
7. 一個動作的起因常常是由一個過去分詞短語來表達的；而一個同時進行的動作常常是由現在分詞短語來描述。
但有時現在分詞短語也能表示一個事件的起因：
Driving through the busy streets like a madman, he was stopped by the police.
分詞ing短語特別適合用來表示生動的、動作中的狀態，也可以用來描述同時發生的事情。試比較下面兩句的差別：
Water lifted her body, caressed it, and carried her out into a misty sea.
(有動作的先后)
Water lifted her body, caressing it, and carried her out into a misty sea.
(是伴隨的狀態)
通常定義或識別一樣事物的方法就是描述它的性質，比如：
The Fresh Air Fund is a nonprofit organization.
The Fresh Air Fund gives impoverished New York City kids the chance to enjoy hills, animals, and trees.
8. 通常象這樣的整句是正確的。不過有時給一個名詞下細節定義的時候，可以通過使用同位語從句更簡潔有力地進行表達：
↓
The Fresh Air Fund, a nonprofit organization, gives impoverished New York City kids the chance to enjoy hills, animals, and trees.
同位語可以通過補充對名詞下定義的細節來明確并拓展名詞的意思。但是，它們的范圍僅限于在同一個從句中，而不能是與名詞隔開的句子或從句。換句話說，同位語能減少使用的從句數量并同時使剩下的從句變的更完整，更充實也更緊湊。
9. 在多種多樣的合并句子的方法中，請記得獨立主格是非常適合用來添加細節的。而把兩句話用獨立主格合并有兩種方法。一是刪除to be的謂語結構—比如is, are, was, or were。通過這種方法，完整句“Her head was slightly lowered over a pile of chemistry notes”就可以變成這樣的獨立主格：“Her head slightly lowered over a pile of chemistry notes.” 第二種方法是把主要動詞變為-ing形式。如上期作業中的第三句：
The station wagon sped away.
The taillights disappeared into the distance.
↓
The station wagon sped away, the taillights disappearing into the distance.
獨立主格通常在句中或句末能更為有效地發揮作用，能為之前的陳述提供更好的細節。請看下例：
The accountant sat quietly in the office.
His eyes were closed.
我們可以用一個獨立主格取代有were的第二個完整句并使his eyes closed附在第一句上：
The accountant sat quietly in the office, his eyes closed.
如果愿意，我們還能省略“his”：
The accountant sat quietly in the office, eyes closed.
10. 分詞短語能給人以生動形象的細節描述，使文章充滿樂趣。但我們該在什么時候在句中加入分詞短語呢？總的來說，要盡可能地把它們放置在離它們相關和修飾的詞最近的位置。請看例句：
She was driving without a license.
She was arrested and jailed by the sheriff.
↓
Driving without a license, she was arrested and jailed by the sheriff.
黑體字部分稱為“懸垂分詞”。
請注意，如果不重視該規則的話，寫出來的可能就會是晦澀難懂的怪句子：
Driving without a license, the sheriff arrested and jailed her. (×)
但請注意和獨立主格連在一起的逗號，或者象是破折號一類的是不能被刪除的。還有，邏輯關系也是值得注意的，時間先后順序不能顛倒哦。
總的來說，獨立主格在句子的當中或是末尾的效果最好，但是，如果要表示原因或者結果的話就一定要放在句子的開頭才有效果。
與分詞短語和同位語一樣，獨立主格也可以連續使用，為渲染氣氛制造強有力的效果：
The arrested woman was slammed against a wall, her body frisked, her wrists handcuffed, her dignity lost.