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。

一般现在时的被动语态的概念：

表示的是一般现在时态和被动语态的叠合。构成：（am/is/are +done）
如：This shirt is washed once a week. 这件T恤一周洗一次。

主动语态变被动语态的方法：

1、把主动语态的宾语变为被动语态的主语。　　
2、把谓语变成被动结构(be＋过去分词)，根据被动语态句子里的主语的人称和数，以及原来主动语态句子中动词的时态来决定be的形式。　　
3、把主动语态中的主语放在介词by之后作宾语，将主格改为宾格。
例如：All the people laughed at him.=He was laughed at by all people. 　　
            They make the bikes in the factory.=The bikes are made by them in the factory. 　　
记忆歌诀：
宾变主，主变宾，by短语后面跟。
谓语动词变被动，be后“过分”来使用。　　

含有情态动词的被动语态：

含有情态动词的主动句变成被动句时，由“情态动词＋be＋过去分词”构成，原来带to的情态动词变成被动语态后“to”仍要保留。　　
记忆歌诀：
情态动词变动，情态加be加“过分”，原来带to要保留。
例如：We can repair this watch in two days.=This watch can be repaired in two days. 　　
            You ought to take it away.=It ought to be taken away. 　　
            They should do it at once.=It should be done at once.

被动语态的用法：
　　
1、不知道或没有必要说明动作的执行者是谁。
例如：Some new computers were stolen last night.一些新电脑在昨晚被盗了。(不知道电脑是谁偷的) 　　
            This book was published in1981.这 本书出版于1981年。　　
2、强调动作的承受者，而不强调动作的执行者。
例如：This book was written by him. 这本书是他写的。　　
            Eight hours per day for sleep must be guaranteed. 每天8小时睡眠必须得到保证。　　
记忆歌诀：
谁做的动作不知道，说出谁做的没有必要；动作承受者需强调，被动语态运用到。

一般现在时的被动语态：

一、被动语态的结构：
主语(动作接受者)+is/am/are+动词的过去分词+(by+动作执行者)
如：Football is played in most countries in the world.
被动语态的句型总结如下：
1、肯定句：主语+be+过去分词+(by~~).
如：The boy is called Jack.
2、否定句：主语+be not+过去分词+(by~~).
如：The baby is not looked after by his father.
3、一般疑问句：Be+主语+过去分词+(by~~)?
如：Is KingLear written by Shakespeare?
4、特殊疑问句：特殊疑词+be+过去分词+(by~~)?
如：What is this kind of sweater made of?

二、被动语态的用法：
1、要表达“被…”、“受…”、“让…”、“遭…”之类的语义。
如：The teachers are well respected. 
        The child is well loved by people.
2、强调动作承受者。
如：He is known far and wide. 他远近闻名。
3、不知道式没有必要指出动作的执行者。
如： The room is cleaned every day. 房子每天都有人打扫。
4、为礼貌起见避免提及动作执行者。
如：I wonder if I was allowed to introduce myself? 我是否可以做自我介绍?