现在分词的概念：

现在分词（PresentParticiple）(又称-ing形式)，是分词的一种，是非限定动词，即在句子里面不能单独充当谓语，但能充当其它的一些成分（定语，表语，补语和状语）。一般式：doing；一般被动式：being done；完成式：having done；完成被动式：having been done。所有否定式都是在－ing前面加not。

现在分词的用法：

1）做表语：
如：He was very amusing.
        That book was rather boring.
很多动词的现在分词都可以作表语：exciting, interesting, encouraging, disappointing, confusing, touching, puzzling.
2）作定语：
上面所出现的现在分词都可以用作定语,修饰一个名词：
如：That must have been a terrifying experience.
        I found him a charming person.
现在分词短语还可以放在名词的后面修饰名词,相当于一个定语从句：
如：There are a few boys swimming in the river.
        There is a car waiting outside.
3）作状语：
现在分词短语可以表示一个同时发生的次要的或伴随的动作：
如：Following Tom, we started to climb the mountain. 
        Opening the drawer, he took out a box.
        Taking a key out of his pocket, he opened the door.
现在分词短语还可以表示原因，相当于一个原因状语从句：
如：Not knowing her address, we couldn't get in touch with her.
        Being unemployed, he hasn't got much money.
现在分词短语还可以表示时间，相当于一个时间状语从句：
如：Hearing the news, they all jumped with joy.
        Returning home, he began to do his homework. 
        Jim hurt his arm while playing tennis.
        Be careful when crossing the road.
        Having found a hotel, we looked for some where to have dinner.
        Having finished her work, she went home.
4）作宾补：
现在分词在一些动词之后可以做宾语的补语：
例如：see, hear, catch, find, keep, have等。
如：I see him passing my house every day.
        I caught him stealing things in that shop.
        I smelt something burning.
        She kept him working all day.

现在分词其他用法解析：

1、现在分词一般式的用法：
现在分词的一般式所表示的动作与主语动作同时发生：
如：When we arrived, we found him sleeping. 我们到达时发现他在睡觉。
         Living in the 示的动作也可略早于或迟于谓语动作，但两者之间没有时间间隔：
如：Seeing nobody at home, he decided to leave a note. 发现没有在家，他决定留个字条。 
         He went home, finding the door locked. 他回到家，发现门是锁着的。当现在分词所表示的动作略迟于谓语动作时，现在分词通常位于句末。

2、现在分词完成式的用法：
现在分词的完成式主要表示发生在谓语动作之前的动作：
如：Having been there once, she knew the place quite well. 由于去过那儿一次，她对那地方很熟悉。
        Having failed twice, he didn't want to try again. 他已经失败了两次，不想再试了。
注：（1）现在分词的一般式和完成式均可表示已完成或先于谓语的动作，但有区别：现在分词所表示的动作虽然可以先于谓语动作，但两者之间没有时间间隔，而现在分词的完成式所表示先于谓语的动作则与谓语动作有一定的时间间隔：
如：Locking the door, he went out. 锁好门之后，他就出去了。
        Having invited him here to speak, we'd better go to his lecture. 既然我们请了他来作报告，我们最好去听一下。
有时即使是分词动作与谓语动作几乎同时发生，但如果要强调分词动作的完成性，也应用现在分词的完成式：
如：Having bought our tickets, we went into the theatre. 我们买好票后就走进剧场。
（2）现在分词的完成式一般不用作定语：
误：Do you know anyone having lost a cat? 你知道有谁丢了一只猫吗？
误：I want to talk to the person having broken the window. 我想同打破窗户的人谈谈。
若将以上现分词的完成式改为一般式也不可以（因为现在分词作后置定语时通常只表示与谓语动作同时或几乎同时发生的动作，而不能先于谓语动作而发生）：
误：I want to talk to the person breaking the window.

3、现在分词被动式的用法：
当要表示一个被动动作时，现在分词就用被动形式。现在分词的一般式和完成式均有被动式形式：
（1）现在分词一般式的被动式：主要表示现在正在进行的动作，也可表示与谓语动作同时发生的动作：
如：Who is the woman being operated on? 正在动手术的女人是谁?
         I saw him being taken away by the police. 我看见他被警察带走。
注：有时现在分词一般式的被动式所表示的动作也可发生在谓语动作之前（此时的现在分词通常用于表示原因，且多为状态动词）：
如：Not having a car, he finds it difficult to get around. 由于没车，她感到行动很困难。
（2）现在分词完成式的被动式：主要表示发生在谓语动词之前且已经完成的动作。
如：The subject having been opened, he had to go on with it. 话题已经开始了，他不得不谈下去。
        Having been written inhaste, the book has many mistakes. 这书因写得仓促，所以错误不少。
比较：Being so ill, she can't go to school. 由于病得那么严重，她不能去上学。
            Having been ill for a long time, he needed time to recover. 由于病了很长时间，他需要一段恢复的时间。

动名词概念：

动名词是一种兼有动词和名词特征的非限定动词。它可以支配宾语，也能被副词修饰，动名词有时态和语态的变化。

现在分词和动名词用法比较：

动词的-ing形式包括现在分词和动名词两种形式。他们的句法功能如下：
动词的-ing形式如果作句子的主语或者宾语时，应该是动名词形式；如果作补语或者状语时，应该是现在分词形式。那么作表语或者定语的动名词和现在分词又该怎样区分呢？
1、动名词与现在分词作表语时的比较：
（1）动名词作表语说明主语的内容，回答what的问题；现在分词作表语相当于形容词作表语，说明主语的性质、特征等，回答how的问题。
如：One of the best exercises is swimming. 游泳是最好的运动项目之一。 
        What pleases him most is bathing in the sea. 最使他高兴的事是在海中沐浴。 
        The situation both at home and abroad is very in-spiring. 国内外的形势都很鼓舞人心。
        The color is pleasing to the eye. 颜色悦目。
（2）动名词作表语，表语和主语几乎处于同等地位，可以互换位置，其句意不变；现在分词作表语，表语和主语则不能互换位置。
如：Our work is serving the people.
      （＝Serving the people is our work.）我们的工作是为人民服务。 
        The news was disappointing. 那消息令人失望。
（3）作表语的现在分词前可以用very，quite，rather，greatly等副词修饰，而动名词则不可以。
如：What he said was very encouraging. 他的话很鼓舞人心。
        Our goal is realizing the four modernizations in the near future. 我们的目标是在不久的将来实现四个现代化。
（4）现在分词与形容词一样可以和more，the most构成形容词的比较级和最高级，而动名词则不可以。
如：The story is the most fascinating. 那个故事最迷人。
（5）作表语用的现在分词除了和be连用以外，还可以和其它的系动词连用；而作表语的动名词则通常只能和be连用。
如：His speech seems inspiring．他的演讲似乎很鼓舞人心。
        His interest is writing for the news papers. 他的爱好是给报社写文章。
（6）有些用作表语的现在分词已经形容词化了。常见的有：exciting，moving，inspiring，missing，interesting，disappointing等。
2、动名词与现在分词作定语时的比较：
（1）动名词作定语时，表示它所修饰的名词的性能和用途，和它所修饰的名词在逻辑上没有主谓关系；
现在分词作定语时，表示它所修饰的名词正在进行的动作，和它所修饰的名词在逻辑上有主谓关系，常可以扩展成一个定语从句。
如：a swimming girl＝a girl who is swimming 一个在游泳的姑娘
        a walking stick＝a stick that is used for walking 一根拐杖
（2）现在分词作定语有时可以后置，而动名词则通常只能放在它所修饰的名词之前。
如：The girl wearing glasses is one of his students. 戴眼镜的那个女孩是他的一个学生。
        I bought some reading materials. 我买了一些阅读材料。

 动名词的用法：

1、作主语：
例如：Fighting broke out between the South and the North. 南方与北方开战了。　
2、作宾语：　　
a. 有些动词可以用动名词作宾语。
例如：admit承认 appreciate感激 avoid避免 complete完成 consider认为 delay耽误 deny否认 detest讨厌 endure忍受 enjoy喜欢 escape逃脱 fancy想象 finish完成 imagine想象 mind介意 miss想念 postpone推迟 practice训练 recall回忆 resent讨厌 resume继续 resist抵抗 risk冒险 suggest建议 face面对 include包括 stand忍受 understand理解 forgive宽恕 keep继续
例如：Would you mind turning down your radio a little, please? 你把收音机音量调小一点，好吗？
      　 The squirrel was lucky that it just missed being caught. 这松鼠幸运得很，刚逃避了被逮住的厄运。　　　　　
b. 有些结构后面可以用动名词作宾语或其他成分。
例如：admit to  prefer...to   burst out   keep on   insist on   count on   set about   put off   be good at   take up   give up   be successful in   be used to   lead to  devote oneself to   object to  stick to  no good   no use be fond of   look forward to  be proud of   be busy   can't help  be tired of   be capable of   be afraid of   think of
3、作表语，对主语说明、解释：
例如：Her job is washing, cleaning and taking care of the children. 她的工作是洗刷、清扫和照顾孩子。
比较：She is washing, cleaning and taking care of the children.
4、作定语，一般表示所修饰名词事物的用途：
例如：a writing desk=a desk for writing 写字台
            a swimming pool=a pool swimming 游泳池
有些动名词作定语，与所修饰的名词关系比较复杂。
例如：boiling point=a temperature point at which something begins to boil 沸点
            a walking tractor=a tractor which a driver can operate while he or she is walking behind it 手扶拖拉机

动名词知识体系：

动名词与不定式用法对比：

过去分词的概念：

过去分词一般表示完成和被动的动作，只有一种形式。即：动词原形加-ed构成。
如：fallen leaves 落叶 
        boiled water 开水
        I heard the door closed. 我听见门被关上了。

过去分词与现在分词被动式的区别：

两者均可表示被动，其区别主要在于它们所表示的时间概念不同，但有时它们也可表示相同的意思。
如：Written in haste, the book has many mistakes. 这书因写得仓促，所以错误不少。 
        Being written in haste, the book has many mistakes. 这书因写得仓促，所以错误不少。 
        Having been written in haste, the book has many mistakes. 这书因写得仓促，所以错误不少。
有时虽然所表示的时间概念相同，但有细微区别：
如：Having been show the lab, we left. 被领着看了实验室后，我们就离开了。

过去分词的句法功能：

1、作定语：
如：I don't like the book written by Martin.
       Our class went on an organized trip last Monday. 上周一我们班开展了一次有组织的旅行。 
注意：当过去分词是单词时，一般用于名词前，如果是过去分词短语，就放在名词的后面。过去分词做定语相当于一个被动语态的定语从句。
2、过去分词作表语：
如：They were very excited at the news. 听到这个消息，他们非常激动。
        The window is broken. 窗户破了。
        They were frightened at the sad sight. 他们对眼前悲惨的景象感到很害怕。
注意：be+过去分词，如果表示状态是系表结构，如果表示被动的动作是被动语态。
区别：The window is broken.（系表）
            The window was broken by the boy.（被动）
有些过去分词是不及物动词构成的，不表示被动，只表示完成。
如：boiled water（开水） fallen leaves（落叶） newly arrived goods（新到的货） the risen sun（升起的太阳） the changed world（变了的世界）
这类过去分词有：gone, come, fallen, risen, changed, arrived, returned, passed等。
3、过去分词作宾语补足语：
如：I heard the song sung several times last week. 上周我听见这首歌被唱了好几次。
有时过去分词做with短语中的宾语补足语：
如：With the work done, they went out to play. 工作做完了，他们出去玩去了。
4、过去分词作状语：
如：Praised by the neighbours, he became the pride of his parents.  受到邻居们的表扬，他成为父母的骄傲。（表示原因）
        Onceseen, it can never be forgotten. 一旦它被看见，人们就忘不了。（表示时间）
        Given more time, I'll be able to do it better. 如果给予更多的时间，我能做得更好。（表示条件） 
        Though told of the danger, he still risked his life to save the boy.  虽然被告之危险，他仍然冒生命危险去救那个孩子。（表示让步） 
        Filled with hopes and fears, he entered the cave. 心中充满了希望与恐惧，他走进山洞。
5、过去分词与逻辑主语构成独立主格：
如：All books returned at the end of the term, the library assistant was satisfied. 所有的书期末时都还了，图书管理员很高兴。
        The field ploughed, he began to spread seed. 地耕好了，他开始撒种子。

现在分词与过去分词的区别：

1、分词作表语：
分词做表语有两种情况，一种是现在分词做表语，一种是过去分词做表语，这两者区别是考试中经常考到的地方。一般来说，表示心理状态的动词如excite，interest等都是及物动词，汉语意思不是“激动”，“高兴”，而是“使激动”、“使高兴”，因而现在分词应该是“令人激动的”、“令人高兴的”，过去分词则是“感到激动的”和“感到高兴的”。所以，凡表示“令人……的”都是-ing形式，凡是表示“感到……”都用-ed形式。换句话说，若人对……感兴趣，就是somebody is in terestedi n...，若人/物本身有兴趣时，就是说sb./sth. is interesting。这类词常见的有：
interesting 使人感到高兴—interested感到高兴的 
exciting令人激动的—excited感到激动的
delighting令人高兴的—delighted感到高兴的 
disappointing令人失望的—disappointed感到失望的
encouraging令人鼓舞的—encouraged感到鼓舞的
pleasing令人愉快的—pleased感到愉快的
puzzling令人费解的—puzzled感到费解的
satisfying令人满意的—satisfied感到满意的
surprising令人惊异的—surprised感到惊异的
worrying令人担心的—worried感到担心的
如：Travelling is interesting but tiring. 旅行是有趣的，但是使人疲劳。
        The pupils will get confused if they are made to learn too much. 如果要学生学得太多，他们会感到糊涂的。 
        The game is exciting. (现在分词作表语)
        We were excited at the news. (过去分词作表语)

2、分词作定语：
分词作定语时有下面几个特点：
1)现在分词表示主动意义，过去分词一般表示被动含意。
2)现在分词表示正在进行，过去分词表示状态或做完(完成)的事。
如：He rushed into the burning house. 他冲进了正在燃烧着的房子。
        The child standing over there is my brother. 站在那儿的男孩子是我弟弟。
        The room facing south is our classroom. 朝南的房间是我们的教室。
        He is an advanced teacher. 他是个先进教师。
3)下列不及物动词也以过去分词形式做定语或表语，但不具有被动意义，这点要注意：
departed, elapsed, faded, fallen, gone, frown-up, retired,  returned, risen, set, vanished, much-traveled, newly-arrived, recently-come

3、分词作状语：
现在分词做状语与过去分词做状语的最主要区别在于两者与所修饰的主语的主动与被动关系的区别。
1)现在分词作状语时，现在分词的动作就是句子主语的动作，它们之间的关系是主动关系。
如：He went out shutting the door behind him. 他出去后将门随手关上。
        Not knowing what to do, he went to his parents for help. 由于不知如何办是好，他去找父母帮忙。
        Smiling, they came in.
2)过去分词作状语时，过去分词表示的动作是句子主语承受的动作，它们之间的关系是被动关系。
如：Cleaned, the room looks nice.
        Given more attention, the trees could have grown better.  如果对这些树多关心一些，它们本来会长得更好。
        Faced with difficulties, we must try to overcome them. 在遇到困难的时候，我们必须设法克服。

虚拟语气的概念：

虚拟语气用来表示说话人的主观愿望或假想，所说的是一个条件，不一定是事实，或与事实相反。在条件句中的应用条件句可分为两类，一类为真实条件句，一类为非真实条件句。非真实条件句表示的是假设的或实际可能性不大的情况，故采用虚拟语气。

虚拟语气在条件句中的应用：

一、真实条件句：
真实条件句真实条件句用于陈述语气，假设的情况可能发生，其中if是如果的意思。
时态关系句型：条件从句：一般现在时；主句：shall/will+动词原形
如：If he comes, he will bring his violin.
典型例题：
The volleyball match will be put off if it___.
A. will rain
B. rains
C. rained
D. is rained
答案：B。真实条件句主句为将来时，从句用一般现在时。
注意：1）在真实条件句中，主句不能用be going to表示将来，该用shall, will。
如： （错） If you leave now, you are never going to regret it. 
         （对） If you leave now, you will never regret it.
            2）表示真理时，主句谓语动词便不用shall(will)+动词原形，而直接用一般现在时的动词形式。

二、非真实条件句：
非真实条件句表示的是假设的或实际可能性不大的情况，故采用虚拟语气。 
1）时态：可以表示过去，现在和将来的情况。它的基本特点是时态退后。
a. 同现在事实相反的假设。
句型：从句：一般过去时；主句：should(would)+动词原形
如：If they were here, they would help you.
b.表示于过去事实相反的假设。
句型：条件从句：过去完成时；主句：should(would)have+过去分词
如：If she had worked harder, she would have succeeded.
        The rice would not have been burnt if you had been more careful.
        If my lawyer had been here last Saturday, he would have prevented me from going.
c.表示对将来的假想句型：
条件从句：一般过去时；主句：should+动词原形
                   从句： were+不定式；主句：would+动词原形 should+动词原形
如：If you succeeded, everything would be all right.
        If you should succeed, everything would be all right.
        If you were to succeed, everything would be all right.

三、混合条件句：
主句与从句的动作发生在不同的时间，这时主，从句谓语动词的虚拟语气形式因时间不同而不同，这叫做混合条件句。
如：If you had asked him yesterday, you would know what to do now. （从句与过去事实相反，主句与现在事实相反。）
        If it had rained last night (过去), it would be very cold today (现在).

比较if only与only if：

only if表示“只有”；if only则表示“如果……就好了”。If only也可用于陈述语气。
如：I wake up only if the alarm clock rings. 只有闹钟响了，我才会醒。
        If only the alarm clock had rung. 当时闹钟响了，就好了。
        If only he comes early. 但愿他早点回来。 
It is(high) time that It is(high) time that 后面的从句谓语动词要用过去式或用should加动词原形，但should不可省略。
如：It is time that the children went to bed.
        It is high time that the children should go to bed. 
need“不必做”和“本不该做"”
didn't need to do表示：过去不必做某事，事实上也没做。
needn'thavedone表示：过去不必做某事，但事实上做了。
如：John went to the station with the car to meet Mary, so she didn't need to walk back home.
        约翰开车去车站接玛丽，所以她不必步行回家了。   
        John went to the station with the car to meet Mary, so she needn't have walked back home.
        约翰开车去车站接玛丽，所以她本不必步行回家了。(Mary步行回家，没有遇上John的车。)
典型例题：
There was plenty o ftime. She___.
A. mustn't have hurried
B. couldn't have hurried
C. must not hurry
D. needn't have hurried
答案：D。needn't havedone. 意为"本不必"，即已经做了某事，而时实际上不必要。 Mustn't have done用法不正确，对过去发生的事情进行否定性推断应为couldn't have done,“不可能已经”。must not do不可以（用于一般现在时）

特殊的虚拟语气词should 的用法：

1）It is demanded/necessary/a pity+that…结构中的主语从句的谓语动词要用should加动词原形，should可省略。
句型：
如：It is suggested that we(should) hold a meeting next week.
        It is necessary that he(should) come to our meeting tomorrow.
2）在宾语从句中的应用在表示命令、建议、要求等一类动词后面的从句中。order, suggest, propose, require, demand, request, insist, command, insist+(should)do
如：I suggest that we(should) hold a meeting next week. 
       He insisted that he(should) be sent there.
注意：如suggest, insist不表示“建议”或“坚持要某人做某事时”，即它们用于其本意“暗示、表明”、“坚持认为”时，宾语从句用陈述语气。
如：The guard at gate insisted that everybody obey the rules.
判断改错：（错）You pale face suggests that you(should) be ill. 
                    （对）Your pale face suggests that you are ill.
                    （错）I insisted that you(should) be wrong.
                    （对）I insisted that you were wrong.
3）在表语从句，同位语从句中的应用在suggestion, proposal, idea, plan, order, advice等名词后面的表语从句、同位语从句中要用虚拟语气，即（should）+动词原形。
如：My idea is that we(should) get more people to attend the conference.
        I make a proposal that we(should) hold a meeting next week.

虚拟语气知识体系：

虚拟条件句的倒装：

虚拟条件句的从句部分如果含有were, should, 或had, 可将if省略，再把were, should或had移到从句句首，实行倒装。
如：Were they here now, they could help us.=If they were here now, they could help us.    
        Had you come earlier, you would have met him=If you had come earlier, you would have met him.    
        Should it rain, the crops would be saved.=Were it to rain, the crops would be saved.
注意：在虚拟语气的从句中，动词“be”的过去时态一律用“were”，不用was，即在从句中be用were代替。
如：If I were you, I would go to look for him.  如果我是你，就会去找他。
        If he were here, everything would be all right. 如果他在这儿，一切都会好的。
典型例题：_____to do the work, I should do it some other day. 
                   A. If were I
                   B. I were  
                   C. Were I  
                   D. Was I
答案：C. 在虚拟条件状语中如果有were, should, had这三个词，通常将if省略，主语提前，变成were, should, had+主语的形式。
但要注意，在虚拟条件状语从句中，省略连词的倒装形式的句首不能用动词的缩略形式。如我们可说Were I not to do.，而不能说Weren't I to do。