SAT语法考点：独立主格

独立主格有以下三个特点：
　　1.独立主格结构的逻辑主语与句子的主语不同，它独立存在。
　　2.名词或代词与后面的形容词、副词、介词短语、分词、不定式等存在逻辑上的主谓关系。
　　3.独立主格结构一般用逗号与主句离开，但与主句之间不能使用任何连接词。
　　独立主格结构本身不是句子，在句子中作状语, 其作用相当于一个状语从句，常用来表示时间、原因、条件、行为方式或伴随情况等。例如：

表示时间
　　The meeting being over, all of us went home. 开完会后我们都回家了。
　　表示条件
　　The condition being favorable, he may succeed. 若条件有利，他或许能成功。
　　表示原因
　　He wrapped her up with great care, the night being dark and frosty. 夜又黑又冷，所以他把她裹得严严实实的。
　　表示伴随情况
　　Almost all metals are good conductors, silver being the best of all. 几乎所有的金属都是良导体，而银则是最好的导体。(=Almost all metals are good conductors, and silver is the best of all.)

一般独立主格形式
　　1)与主句逻辑关系松散
　　A:  n. + -ed/-ing形式
　　名词/主格代词+现在分词 (名词/主格代词与现在分词之间是主动关系。)
　　如：The girl staring at him(= As the girl stared at him), he didn't know what to say.
　　名词/主格代词+过去分词 (名词/主格代词与过去分词之间是被动关系。)
　　如：The problems solved(= As the problems were solved), the quality has been improved.

B:  n. + 不定式
　　名词/主格代词+不定式 (名词/主格代词与不定式之间是主动关系，且强调的是一次具体性的动作。)
　　如：He is going to make a model plane, some old parts to help.
　　C:  n. + 形容词
　　名词/主格代词+形容词
　　如：An air accident happened to the plane, nobody alive.

D:  n. + 副词
　　名词/主格代词+副词
　　如：The meeting over, they all went home.
　　E:  n+介词短语
　　名词/主格代词+介词短语
　　如：The boy goes to the classroom, book in hand.

以上是最常见的几种形式，尤其是A的形式

2) with 引导的独立主格:与主句逻辑关系紧密
　　形式为: with + n. + -ed/-ing形式; with + n. +adj.; with +n. + 介词短语
　　[OG-2 section6-8 Page:470]
　　3) each引导的强调型独立主格:强调句尾的复数名词
　　形式为:句子 + 复数名词结尾 , each + 介词短语/形容词短语/名词短语/-ing形式/-ed形式
　　The African continent comprises more than 50 countries, each diverse in their cultures and languages.
　　(A) diverse in their
　　(B) diverse in its
　　(C) is diverse in its
　　(D) of them being diverse in their
　　(E) having diversity in their

4) 其他形式
　　There being +名词(代词)
　　An odd friendship in certain respects, she being an outdoor enthusiast and he a dedicated bookworm.  [2012-01-Section6-no9]
　　(A) An odd friendship
　　(B) As an odd friendship
　　(C) Their friendship being odd
　　(D) Theirs was an odd friendship
　　(E) Having a friendship that was somewhat odd
　　　
　　The island of Madagascar, off the coast of Africa, is the habitat of more than 200,000 species of plants and animals, many are not found anywhere else on the planet.[ 2012-01-Section6-no11]
　　(A) animals, many are not found anywhere
　　(B) animals; many, not found anywhere
　　(C) animals; of which many are not found anywhere
　　(D) animals, many found nowhere
　　独立主格结构曾经出现过
　　(09-05-Section4-no.24; 09-05-Section10-no.10)(12-01-Section6- no9/no11)