1. 即使是因为意思上的需要而使得我们只能选择某一句作为从属子句，我们依旧有选择从属连词的机会：
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.
这里的because和since表原因，after表时间。
请学习下面例句中各种形式含义的从属子句：
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，当介词短语修饰的是一个较短的主语，那么该短语可以出现在该名词的任意一边，请看下例：
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. 两句谓语结构类似的句子要合并的话，其中一个往往会使用到介词——通常有after, aside from, before, besides, by, for, in,或者without——后面紧跟现在分词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.
介词with有时被用来引导独立主格：
We crossed the river by ferry.
The bus accompanied us.
↓
We crossed the river by ferry, with the bus accompanying us.
4. 介词短语可以被用来构造平行结构，无论是通过配对的介词或是同一个介词一系列的重复，都是可行的。使用配对介词比如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.
而一系列的同一介词的使用，可以用来列举平行的观点：
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. 外表与介词短语相似的是副词不定式。这些不定式通常由介词to 或in order to引导，后面跟随的对象是动词原形： to see, to write, to daydream副词不定式通常表示一个目的，目标或是决心，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
通常情况下，不定式被默认为和句子的其他成分有着同一个主语，特别是不定式较短的时候。但这一规则经常被忽略，尤其是使用了通用的习惯用法，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.
不定式做状语既可以在句子的末尾也可以放在句子的开头：
Medical students serve an internship in order to gain first-hand experience before they officially enter into a medical career.
它们也可以放在句子中间，前后用逗号隔开，表插入语：
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.
有时一个插入的不定式通过迫使读者在它们之前停顿一下而达到特殊的强调效果。但该用法通常是在文学中使用，只作为欣赏，不建议大家使用：
Man is, to use the author’s own term, a superprimate.
不定式也能多个出现，既可在主句之前，也可在主句之后。在多个出现的不定式短语中，除第一个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.
最后一个例子说明了不定式做状语比用其他方法更为简洁和雅致的优点：
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
但请注意和独立主格连在一起的逗号，或者象是破折号一类的是不能被删除的。还有，逻辑关系也是值得注意的，时间先后顺序不能颠倒哦。
总的来说，独立主格在句子的当中或是末尾的效果最好，但是，如果要表示原因或者结果的话就一定要放在句子的开头才有效果。
6. 与分词短语和同位语一样，独立主格也可以连续使用，为渲染气氛制造强有力的效果：
The arrested woman was slammed against a wall, her body frisked, her wrists handcuffed, her dignity lost.
当我们所要代替的名词是专有名词（某人的名字或某物的名称）时，必须在这前后加上逗号：
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，关系从句通过增加细节来修饰名词。而细节则能使作品更生动有力。
关系从句通常可以被简化成其他更紧凑或是更有效的结构：
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. 一个动作的起因常常是由一个过去分词短语来表达的；而一个同时进行的动作常常是由现在分词短语来描述。
但有时现在分词短语也能表示一个事件的起因：
Driving through the busy streets like a madman, he was stopped by the police.
分词ing短语特别适合用来表示生动的、动作中的状态，也可以用来描述同时发生的事情。试比较下面两句的差别：
Water lifted her body, caressed it, and carried her out into a misty sea.
(有动作的先后)
Water lifted her body, caressing it, and carried her out into a misty sea.
(是伴随的状态)
通常定义或识别一样事物的方法就是描述它的性质，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. 通常象这样的整句是正确的。不过有时给一个名词下细节定义的时候，可以通过使用同位语从句更简洁有力地进行表达：
↓
The Fresh Air Fund, a nonprofit organization, gives impoverished New York City kids the chance to enjoy hills, animals, and trees.
同位语可以通过补充对名词下定义的细节来明确并拓展名词的意思。但是，它们的范围仅限于在同一个从句中，而不能是与名词隔开的句子或从句。换句话说，同位语能减少使用的从句数量并同时使剩下的从句变的更完整，更充实也更紧凑。
9. 在多种多样的合并句子的方法中，请记得独立主格是非常适合用来添加细节的。而把两句话用独立主格合并有两种方法。一是删除to be的谓语结构—比如is, are, was, or were。通过这种方法，完整句“Her head was slightly lowered over a pile of chemistry notes”就可以变成这样的独立主格：“Her head slightly lowered over a pile of chemistry notes.” 第二种方法是把主要动词变为-ing形式。如上期作业中的第三句：
The station wagon sped away.
The taillights disappeared into the distance.
↓
The station wagon sped away, the taillights disappearing into the distance.
独立主格通常在句中或句末能更为有效地发挥作用，能为之前的陈述提供更好的细节。请看下例：
The accountant sat quietly in the office.
His eyes were closed.
我们可以用一个独立主格取代有were的第二个完整句并使his eyes closed附在第一句上：
The accountant sat quietly in the office, his eyes closed.
如果愿意，我们还能省略“his”：
The accountant sat quietly in the office, eyes closed.
10. 分词短语能给人以生动形象的细节描述，使文章充满乐趣。但我们该在什么时候在句中加入分词短语呢？总的来说，要尽可能地把它们放置在离它们相关和修饰的词最近的位置。请看例句：
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.
黑体字部分称为“悬垂分词”。
请注意，如果不重视该规则的话，写出来的可能就会是晦涩难懂的怪句子：
Driving without a license, the sheriff arrested and jailed her. (×)
但请注意和独立主格连在一起的逗号，或者象是破折号一类的是不能被删除的。还有，逻辑关系也是值得注意的，时间先后顺序不能颠倒哦。
总的来说，独立主格在句子的当中或是末尾的效果最好，但是，如果要表示原因或者结果的话就一定要放在句子的开头才有效果。
与分词短语和同位语一样，独立主格也可以连续使用，为渲染气氛制造强有力的效果：
The arrested woman was slammed against a wall, her body frisked, her wrists handcuffed, her dignity lost.