问题12.Electrical resistance is a common property of all materials,_____.为什么不能用only differs in degree而是 differing only in degree
  答：又是分词的用法。句子已经有了系表结构的谓语。如果再来一个谓语动词，做什么成分啊？differing only in degree是现在分词，在这里做主补。

  问题13.When I walked in,Grandpa was sitting at the kitchen table,the newspaper_____before him.这里为什么用spread，spreading不是可以表正在吗？
  答：还是分词的用法问题。the newspaper是被spread ，所以用过去分词。整个构成独立主格结构，做句子的状语，表示伴随状况。遇到这种题，最好将它变成完整句子“the newspaper was spread before him"而不是：“the newspaper was spreading before him"
     问题14.Maggie ran back to the kitchen,_____ carefully in her hands.我知道holding the eggs是独立主格，eggs were held为什么不能用，是不是必须简到eggs held in hand 
答：还是分词用法。holding the eggs不是独立主格。是分词短语做状语，与主语Maggie构成主动关系，是她发出的动作。不需要用独立主格。如果用eggs held，就是独立主格了。其中eggs为逻辑主语，held 为过去分词，因为独立主格中要看动词与逻辑主语的关系，主动就用现在分词、被动就用过去分词。如果用eggs were held，这是一个完整的句子，又没有连词，怎么和主句联系啊？记住：英语中，不能靠一个逗号就连接两个句子的。或者用连词，或者用非谓语动词结构等。
  独立主格是英语语法上的一个难点，我在网上查了一些资料，供你参考。多看一些例句，对它有了感性的认识，才能掌握它的用法。
 独立主格的构成是：独立主格结构（Independent Genitive）有两部分组成，前一部份是名词或者代词，后一部分是非谓语动词(不定式、动名词和分词)或形容词、副词、或介词短语。前后两部分具有逻辑主谓关系。独立主格结构在句中做状语，多用于书面语。 独立主格结构本身不是句子，在句子中作状语，表示时间、原因、条件、伴随、目的等。
非谓语动词作状语，其逻辑主语须与主句主语保持一致。若不一致，非谓语动词形式须另带主语，从而构成复合结构的形式作状语。这种结构称为“独立结构”。其中，非谓语动词主动用V-ing，被动用V-ed。 　
 　非谓语动词及其短语前面带有逻辑主语，逻辑主语的代词又是主格，故常称为“独立主格”。“独立结构”在句中起状语作用，相当于状语从句，表示时间、原因、条件、方式或伴随等情况。
　　独立主格结构主要用于描绘性文字中，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。 Her work done, she sat down for a cup of tea. 她干完了活，坐下来喝茶。
表示条件
　　The condition being favourable, he may succeed. 若条件有利，他或许能成功。
表示原因
　　There being no taxis, we had to walk. 没有出租车，我们只好步行。 　　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.)
　　
还有：　　
用作条件状语
　　Weather permitting(=If weather permits), they will go on an outing to the beach tomorrow. 如果天气允许的话，他们将在明天组织一次海滨小游。
用作原因状语
　　An important lecture to be given tomorrow(=As an important lecture will be given tomorrow), the professor has to stay up late into the night. 因为明天要发表一个重要的演讲，教授不得不熬夜到很晚。
用作伴随状语
　　He was lying on the grass,his hands crossed under his head(=and his hands were crossed under his head).他躺在草地上，两手交叉枕在脑后。
表示补充说明
　　We redoubled our efforts, each man working like two. 我们加倍努力，一个人干两个人的活。 　　*注：独立主格结构表示时间、条件或原因时，相当于一个状语从句，一般放在句首，表示原因时还可放在句末；表伴随状况或补充说明时，相当于一个并列句，通常放于句末。

1>一般独立主格形式:与主句逻辑关系松散
　　形式为: n. + -ed/-ing形式; n. + 不定式 ; n. + 介词短语; n. + 形容词; n. + 副词. ;
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谓关系。如：The girl staring at him(= As the girl stared at him), he didn't know what to say. 姑娘两眼望着他，他不知道说什么好。 　　
  Time permitting(= If time permits), we will go for an outing tomorrow. 如果时间允许的话，我们明天去郊游。
名词/主格代词+过去分词
　　名词/主格代词与过去分词之间是动宾关系。如:The problems solved(= As the problems were solved), the quality has been improved. 随着问题的解决，质量已经提高了。 　　

      Her glasses broken(= Because her glasses were broken), she couldn't see the words on the blackboard. 由于眼镜摔坏了，她看不见黑板上的字。
名词/主格代词+不定式
　　名词/主格代词与不定式之间是主谓关系，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. 借助于一些旧零件，他要做一个飞机模型。 　
　They said good-bye to each other, one to go home, the other to go to the bookstore. 他们道别后，一个回了家，一个去了书店。
名词/主格代词+形容词
　　如：An air accident happened to the plane,nobody alive. 那架飞机遭遇了空难，无一人生还。 　　

           So many people absent, the meeting had to be called off. 这么多人缺席，会议不得不取消。
名词/主格代词+副词
　　如：He put on his sweater ,wrong side out. 他把毛衣穿反了。The meeting over, they all went home. 会议一结束，他们就都回家了。
名词/主格代词+介词短语 如：The boy goes to the classroom,book in hand. 那男孩手里拿着书去教室。 　　Mary was sitting near the fire, her back towards the door. 玛丽靠近火炉坐着，背对着门。
 　　
 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. +abj.; with +n. + 介词短语 　
　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 如:Under the restructuring, the huge organization that operates the company's basic businesses will be divided into five groups, each with its own executive.（题源:《GMAT语法全解》白勇著，Page38） 　　
4>其他形式
There being +名词（代词）
　　如： There being nothing else to do, we went home. 没有别的事可做，我们就回家了。 　　There being no further business, I declare the meeting closed. 没有再要讨论的事了，我宣布散会。
It being +名词（代词）
　　如：It being Christmas, the government offices were closed. 由于圣诞节的缘故，政府机关都休息。 　　It being a holiday, all the shops were shut. 由于今天是假日，所有商店都关门了。

独立主格结构特点：
　　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分词，形容词，副词，不定 式，介词等是主谓关系。3）独立主格结构一般有逗号与主句分开。举例：The test finished, we began our holiday. = When the test was finished, we began our holiday. 考试结束了，我们开始放假。 The president assassinated, the whole country was in deep sorrow. = After the president was assassinated, the whole country was in deep sorrow. 　总统被谋杀了，举国上下沉浸在悲哀之中。 Weather permitting, we are going to visit you tomorrow.如果天气允许，我们明天去看你。This done, we went home.工作完成后，我们才回家。The meeting gone over, everyone tired to go home earlier.会议结束后，每个人都想早点回家。He came into the room,his ears red with cold. 　他回到了房子里，耳朵冻坏了。 He came out of the library, a large book under his arm. 他夹着本厚书，走出了图书馆

    注：独立主格结构有时可在其前加上介词with。 如：Don’t sleep with the windows open.别开着窗睡觉。 He was lying on the bed with all his clothes on. 他和衣躺在床上。 She came in with a book in her hand. 她手里拿着一本书走了进来。 He fell asleep with the lamp burning. 他没熄灯就睡着了。I won’t be able to go on holiday with my mother being ill. 因为妈妈有病，我无法去度假。 He sat there with his eyes closed. 他闭目坐在那儿。 All the afternoon he worked with the door locked.整个下午他都锁着门在房里工作。 I can’t go out with all these clothes to wash. 要洗这些衣服，我无法出去了。
注意事项
　　1.独立主格与状语从句的转换当状语从句的主语与主句的主语不是指同一个对象时，可用独立主格结构取代状语从句，但不再保留连词。如：After class was over (=Class being over / Class over), the students soon left the classroom.下课后，学生很快离开了课室。 2. 不能省略being (having been)的情形：在下列两种情况下，独立主格结构中的being（或having been）不能省略。 (1) 独立主格的逻辑主语是代词时。如：It being Sunday, we went to church.因为是星期天，我们去了做礼拜。 (2)在There being＋名词的结构中。如：There being no bus, we had to go home on foot.因为没有公共汽车，所以我们不得不步行回家。 3. 在“名词（或代词）＋介词短语”构成的独立主格结构中，一般不用形容词性物主代词和冠词。如： Miss Smith entered the classroom, book in hand.史密斯小姐走进了课室，手里拿着一本书。比较with的复合结构。如：Miss Smith entered the classroom, with a book in her hand. 4. 独立主格结构没有所有格形式The chief-editor arriving, we began the meeting. 主编来了，我们开始开会。(比较动名词复合结构。)
示例
　　请看下面一道题： Not far from the school there was a garden, _________ owner seated in it playing chess with his little grandson every afternoon. 　　A. its B. whose C. which D. that 　　

【分析】此题很容易误选B，许多同学会认为句中逗号后是一个非限制性的定语从句，whose 在定语从句中用作定语修饰其后的名词 owner。此分析从表面上看，似乎天衣无缝，但实质上是错的，原因是空格后根本不是一个句子，因为没有谓语。尽管句中有两个动词，但它们都是非谓语动词。也许有的同学认为，其中的 seated 可视为谓语动词，但是注意，seat 用作动词时，它总是及物的，其后要么接宾语，要么它就用于被动语态，所以若在 seated 前加上助动词 is，则可以选择B（当然若将 seated 改为sitting，也应选择B）。所以此题最佳答案选A。 　　
  请再看一个类似的例子：(1) He wrote a lot of novels, many of _________ translated into foreign languages. 　　A. it B. them C.which D. that 　(2) He wrote a lot of novels, many of _________ were translated into foreign languages.A. it B. them C. which D. that 　第(1)应选B，而不能选C，是因为句中的 translated 是过去分词(非谓语动词)，若选C，则该从句无谓语；第(2)应选C，该句是典型的非限制性定语从句，因为该句修饰的是前面的novels，即指物，所以只能用which做of的宾语，故本题选C。 　　
 再请看下面一例：(3) He wrote a lot of novels, and many of _________ were translated into foreign languages. A. it B. them C. which D. that 　　【分析】此题与上面的第(2)题不同，两句间多了一个并列连词and，说明这是一个并列句，故应选B，则不能选C。 　
　请做做以下三题(答案均为B)： 　　(1) There I met several people, two of _________ being foreigners. 　　A. which B. them C. whom D. that 　　(2) There I met several people, two of _________ were foreigners. 　　A. which B. whom C. who D. that 　　(3) There I met several people, and two of _________ were foreigners. A. which B. them C. whom D. that