独立主格结构什么意思？
在there be句型中，独立主格结构用在后面，因为be已经是句子的谓语了，所以独立主格结构加在后面，是对there be句型的补充和修饰。例如：There were lots of people in the reading room, most of them with their heads bent over their books. most of them就是独立主格结构。
一、 独立主格结构的含义和实质
“独立主格结构”(absolute construction)又叫“独立结构”，是带有自己主语的非谓语动词分句和无动词分句。由于在语法上有自己的逻辑主语，结构上与主句不发生关系，因此传统语法叫做“独立主格结构”。其实，所谓“独立主格结构”并非真正独立，它还是一种从属分句，与主句紧密联系在一起，共同表达一个完整的意思，通常在句中起状语分句的作用。独立主格结构可放于句首、句尾，用逗号和主句隔开。
二、 独立主格结构的基本形式和功能
独立主格结构可以分为两部分：一部分是名词或代词，起逻辑主语的作用;另一部分是非谓语动词分句(现在分词、过去分词、不定式)或无动词分句(名词、形容词、副词、介词短语)，表示前面名词或代词的动作或状态。
基本形式是：名词普通格/代词主格+现在分词/过去分词/不定式/名词/形容词/副词/介词短语，with引导的复合结构。
1. 名词/代词+ 现在分词
现在分词表示前面的名词或代词主动进行的动作或状态等。
例
His homework having been done, Tom went to sleep.
So many students being absent, the meeting had to be put off.
The man lay there, his hands trembling.
注：“独立结构”中的being或 having been 有时可以省去，这样就成了无动词分句或过去分词分句。
2. 名词/代词+过去分词
过去分词表示前面的名词或代词被动完成的动作或所处的一种状态。
例 The boy lay on his back, his hands crossed under his head.
Her shirt caught on a nail, she could not move.
The job not finished, we couldn’t see the film.
后面两个句子也可以看成省略掉了having been，being。如果加上，这两个句子就又变成了现在分词分句。
3. 名词/代词+不定式
不定式表示的是将来的动作。
例He suggested going for a picnic, Mary to provide the food.
These are the first two books， the third one to come out next month.
We shall get together at 7:30, the procession(游行) to start moving at 8 sharp.
4. 名词/代词+名词
名词一般做前面名词或代词的同位语。
例 Many people joined in the work, some of them women and children.
He fought the tiger，a stick his only weapon.
5. 名词/代词+形容词短语
形容词(短语)说明前面名词或代词的性质，状态，原因等。
例The floor wet and slippery, we had to stay outside for a while.
I heard that she got injured in the accident， my heart full of sorry.
这两个句子也可以看成是省略了being,如果加上，就变成了现在分词分句。
6. 名词/代词+副词
副词说明前面名词或代词的状态。
例 The meeting over, we all went home.
He sat at the table, head down.
Nobody in, he left a message on the board.
7. 名词/代词+介词短语
介词短语说明伴随前面名词或代词的方式或者状态。
例 The teacher came in, a book under his arm.
The hunter entered the forest， gun in hand.
Nobody at home, the thief took a lot of things away.
8. with引导的复合结构, 也可以认为是一种独立主格结构
例 A woman got on the bus with a baby around her arms.
The teacher came in with several students following behind.
With a lot of things to deal with, he will have a difficult time.
Mary rushed out of the house with the door open.
With the work done, he went out to eat.
He left the office with the lights on.
三、 学习独立主格结构应注意的一些问题
1. 独立主格结构中分句和主句的主语不一致
从以上例子可以看出，含有独立主格结构的句子，前后主语是不一致的，这也是独立主格结构和非谓语分句作状语的最重要区别。
例 (1) Hearing the news, he was very excited.
(2) Winter coming, it gets colder and colder.
在这两个句子里，第一个句子，前后的主语是一致的，都是he, 也就是说动词hear的动作发出者是主语he , 因此它是一个现在分词短语作状语表示原因的句子;而第二个句子，我们可以发现，有两个主语，第一个是动词come 的逻辑主语winter, 而第二个主语是句子真正的主语it，非谓语动词coming 和it 之间没有任何关系，因此它是一个独立主格结构。
2. 在独立主格结构中，动词是用现在分词还是过去分词
一般来说如果逻辑主语和动词之间是主谓关系，用现在分词。如：Time permitting, we will go out to play.一句中，time 和 permit 之间是逻辑上的主谓关系--- “时间允许”，因此用现在分词。 如果逻辑主语和动词之间是动宾关系，并且有被动的意思，用过去分词。如：“More time given,we should have done it better. ”一句中，time 和give 之间的关系是动宾关系，有被动的意思---“如果被给更多时间”，因此用过去分词。
3. 独立主格结构相当于一个状语从句
独立主格结构不是一个句子，而是相当于一个状语从句,可以表示时间、原因、条件、方式和伴随情况等。
例 Work done, John went home.相当于一个表示时间的状语从句：When the work has been done, John went home.
例There being no buses, we had to walk home.相当于一个表示原因的状语从句：Because there are no buses, we had to walk home.
4. 完成时态的运用
在独立主格结构中如果强调分词的时间发生在主句动作时间之前，常用现在分词的完成时态having done， 根据情况确定是用主动还是被动。
例
The last bus having gone, we had to walk home.
His wallet having been stolen, he didn’t know what to do next.
