动名词（gerund）和现在分词（present participle）的区别
所谓动名词(gerund)就是名词,只是保有一些动词的功能.所以它在句中可以作主语,宾语,表语,同位语,定语等那些名词可以充当的成分.
而现在分词(present participle)相当于形容词,在句中作定语或者状语
所以当-ing形式出现在句中作主语,宾语,同位语时,它肯定时gerund.
当-ing形式出现在句中作状语时,它肯定是present participle.
它们有可能被弄错的是作表语和定语时.其实也很好区分
1. 作表语: 我们知道, 名词和形容词都可以作表语.
This is water(n.).
It is transparent(adj).
这时你肯定能明白,如果-ing作表语相当于n.它就是gerund. 反之相当于adj.时它就是present.participle.
The situation both at home and abroad is very inspiring.
One of the best exercises is swimming.
2. 作定语时的区别我在回答中已经解释了. 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.
a sleeping bag.(用途)=a bag for sleeping
a sleeping child = a child is sleeping (child是sleep的主语,sleep是child发出的动作)
(呵呵下面再请你告诉我它们分别是什么吧!
a swimming girl
a swimming pool
3. 最后来解释修饰他们到底该用是adv, 还是adj.
无论是Present participle. 还是gerund, 它们都叫做动词的-ing形式(所以若有人分不清它们时,多把它们混为一谈).也就是说它们都有动词的特点,故而都可用adv修饰.
eg: Reading a novel intently, I didn’t realize he came in. (reading, 现分作状语, 用adv intently修饰)
eg: My dream is speaking English perfectly. (speaking动名词,副词perfectly修饰.)
但gerund不仅有动词的特点,它也有名词的特点,这就决定了它也可以像名词一样用物主代词,形容词来修饰.
Would you mind my(物主代词) sitting here?
The mellow(愉快的, 形容词) singing of the birds announces the coming of spring
现在分词和过去分词主要差别在于：现在分词表示“主动和进行”，过去分词表示“被动和完成”(不及物动词的过去分词不表示被动，只表示完成)。分词可以有自己的状语、宾语或逻辑主语等。
表示伴随
1. 分词作状语分词在句子中作状语，可以表示时间、条件、原因、结果（补充说明）、让步、伴随等。分词做状语时，它的逻辑主语与句子的主语一致。作状语的分词相当于一个状语从句。
Eg. Hearing the news, they all jumped with joy.
Using what you know of word stems and word formations, you can make a guess at the meaning of a new word.
The students went out of the classroom, laughing and talking.
Accompanied by his friend, he went to the railway station. Given better attention, the plants could grow better.
He looked tired and depressed, visibly disturbed by the news of his mother's illness.
分词在句子中作状语，使用何种分词，要取决于分词与句子主语的关系：主谓关系用现在分词，动宾或被动关系用过去分词。
Eg. Not shavings enough hands, we turned to them for help.(we don't have enough hands)
Taught by mistakes and setbacks, we have become wiser and handled our affairs better. (we are taught/teach us)
Inspired by Leifeng, the people in China worked very hard to achieve their modernization.
____the earth to be flat, many feared that Columbus would fall off the edge. (CET-4 1996,6)
A) Having believed B) Believing C) Believed D) Being believed
本句意思为：相信地球是平的，许多人担心哥伦布会从边上掉下去。许多人与相信之间是主谓关系，及分词与主语之间为主谓关系。
No matter how frequently ____, the works of Beethoven always attract large audiences. (CET-4 1995, 6)
A) performing B) performed C) to be performed D) being performed
本句中贝多芬的作品被反复表演，可见分词与句子的主语之间是被动关系，应该用过去分词，故答案为B.
____as it was at such a time, his work attracted much attention. (CET-4 1996,1) A) Being published B) Published C) Publishing D) To be published
2)“while ( when, once, until, if , though等连词)＋分词”结构现在分词或过去分词作状语时，有时可以在分词前加while，when, once, although, until, if等连词。
Eg. When leaving the airport, she waved again and again to us.
While waiting for the train, I had a long talk with my sister about her work.
2. 分词作定语分词作定语时，单个的分词通常放在被修饰的名词之前，分词短语一般置于所修饰的中心词后面。现在分词修饰的是发出该动作的名词(与名词有主谓关系)，过去分词修饰承受该动作的名词(与名词是动宾关系)。
Eg. This is really an exhausting day to all of us!
We can see the part of the moon lighted by sunlight.
After a night spent in excitement and sleeplessness, I forced myself to take a long walk along the beach the next day.
More and more developing countries established strategic partnership with developed countries.
The young sitting between my sister and my brother is my cousin Jack.
3. 分词作宾语补足语现在分词在see, watch, hear, observe, notice, feel, find, glimpse, glance等感官动词和look at, listen to等短语动词以及have, keep, get, catch, leave, set, start, send等使役动词后面与名词或代词构成复合宾语，作宾语补语的成分。
【例如】On the top of the hill, we could see smoke rising from the chimneys in the village.
The boy sat beside the railway line and watched the trains roaring by.
We should not leave him wondering what he should do.
I am sorry to have kept you waiting for such a long time.
I caught him doing something else in class.
4. 过去分词可以在allow, ask, consider, desire, expect, feel, find, get, have, hear, imagine, keep, like, make, observe, order, permit, prefer, remember, request, require, see, urge动词等后面作宾语补足语。
【例如】You should keep her informed of what is going on here.
I expected you well prepared for the examination.
在动词see, hear, feel, watch, notice，perceive，observe, listen to, look at后既可用现在分词做补语,也可用不定式做补语。用现在分词表示动作正在进行,用不定式表示的动作的全过程已经完成。
【例】I saw Mr. White get off a bus.
I saw Mr. White looking into a shop window.
——Do you hear someone knocking at the door?
——Yes, I did. I heard him knock three times.
5. 分词作表语分词作表语通常看作形容词来用。现在分词表示主语的性质，而且主语多为物；过去分词表示主语的心理感受或状态，主语多为人。
【例】The film “Harry Potter” is really exciting, and I am excited about it.
His response to the question was quite disappointing. I really felt ______ at his response
追问现在分词为什么相当于形容词，你举的例子Reading a novel intently, I didn’t realize he came in. (reading, 现分作状语, 用adv intently修饰)中，现在分词reading做形容词吗，修饰novel吗
追答reading 在这里不是形容词，是动词，用adv intently修饰。做状语，表示原，翻译为：由于专心于看小说，我都没有意识到他进来了。