大学英语四级考试涉及的语法知识点多、涉及面宽，对不少考生来说都是一个难题。希望通过本文的学习，考生能对四级语法有更全面的掌握!
一 、独立结构的构成：
只有当分词短语的逻辑主语和句子主语不一致时，我们才能用独立结构。独立结构只用做状语，多用于书面语言。常见的独立结构有以下几种：
(一) 名词/代词 分词(包括现在分词和过去分词)：
1 The boy ran quickly, his father following. (表示伴随情况)
2 He lay on his back, his hands acrossed under his head. (表示伴随情况)
(二)名词/代词 形容词：
1、They started home, their minds full of plans for increasing production. (表示伴随情况)
2、 He was silent for a moment, his lips tight. (表示伴随情况)
(三)名词/代词 副词：
1、 He put on his socks, wrong side out. (表示补充说明)
2 、The war over, all the Chinese people’s volunteers came back to China. (表示补充说明)
(四)名词/代词 介词(短语)
1 、She came in, a baby in her arms. (表示伴随情况)
2 、He went off, gun in hand. (表示伴随情况)
二、独立结构在句子中的作用：
独立结构在句子中只能做状语，这种结构可以用来：
(一)表示时间：
His homework done, Jim decided to go and see the play.
(=After his homework was done, he decided to go and see the play.)
(二)表示原因：
The last bus having gone, we had to walk home.
(=Because the last bus having gone, we had to walk home. )
(三)表示条件：
Weather permitting, we’ll go for an outing tomorrow.
(=If weather permitting, we’ll go for an outing tomorrow.)
(四)表示伴随情况或伴随状况：
They walked through the forest, an old hunter leading the way.
(五)表示补充说明：
He lived in a wooden house with two rooms, one being a bedroom and the other being an office.
(=He lived in a wooden house with two rooms, one was a bedroom, the other was an office.)
三、独立变格的变化
在带有逻辑主语的分词及其短语前加”with”
1、——Why are they taking all the equipment away?
——The job_____, they are packing up to leave.
A. it to done B. did C. was did D. done
2、Other things being equal, a man who expresses himself effectively is sure to succeed more rapidly than the man whose command of language is poor.
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