在实际运用中，一般可以互换，差异
不大。但在下列几种情况中不能互换： a. 当表语是动名词时，主语也要用 动名词；当表语是不定式时，主语也 要用不定式 (对等性)如：
2．动名词（短语）作表语，如： Their job is building houses. His job is raising pigs. 注①：动名词作表语与不定式作表语的区别： 1. 动名词作表语时表示比较抽象的一般行为、习惯； 2.不定式作表语时表示具体的某一次动作，特别是将来的动作，试
To do that sort of thing is foolish。
主语
动 词 不 定 式
I want to see you this evening.
All you have to do is to finish it quickly.
宾语 表语
We found a house to live in.
动 名 词
动名词
非 谓 语 动 词
现在分词 分 词 过去分词
不定式
不定式: 具有n. adj. adv. 特征，
在句中担任除谓语外任何成分； 动名词: 具有n. 特征，在句中可 作主语、宾语、定语、表语； 分词: 具有adj. adv. 特征,在句中 可作主语、表语、宾补、状语；
①有语态和部分时态的变化； ②可以有自己的宾语和状语， 同其宾语和状语一起构成短 语； ③还可有逻辑主语;
My job is teaching. = Teaching is my job. Her full-time job is laying eggs. =Laying eggs is her full-time job.
2．表语
Your task is cleaning the windows.
Their coming to help was a great encouragement to us.
I don’t like Andy’s smoking in the office.
动名词的复合结构作主语 当动名词有自己的逻辑主语时，常可以在前面 加上一个名词或代词的所有格，构成动名词的复 合结构(——这时，名词或代词的所有格做动名词 的逻辑主语)。
另一类是既可以用动名词，又可以用不定
式作宾语的动词，其中有：
begin,
cannot bear, continue, forget, hate, intend, like, love, plan, prefer, propose, regret, remember, start, try, want, need等。
It
is no use crying over spilt milk. It is no point arguing with him about this. 动名词作主语，有时先用it作形式主语，把 动名词置于句末。这种用法在习惯句型中常 用。
It’s no use /no good/no point doing … It’s a waste of time doing … It’s worth doing …
在“There be”结构中，只能用动名词做主语， 而不能用不定式。
3．宾语
一类是只能用动名词作宾语的动词，其中有： avoid, admit, consider, delay, advise, enjoy, escape, excuse, finish, can’t help, imagine, keep (on), mind, miss, practise, stop, go on, suggest 等，
不定式作主语往往特指具体的某此动作，尤其是将来的动作。
e.g) Smoking is harmful to people’s health. (泛指） To solve the problem is out of the question. （特指）
动名词作主语与不定式作主语的区别：
Sweeping the floor every day is the cleaner’s job. (抽象，泛指) To sweep the floor today is my job.（具体）
比较：
My favourite sport is swimming. The first thing for us to do is to improve our pronunciation.
There is no joking about such matters. There is no saying when he'll come.
二、动名词的时态和语态
时态：
如果动名词的动作没有明确的表示出时间是与谓语 动词同时还是在之前发生，用动名词的一般式。 We are interested in listening to music. 如果动名词的动作发生在谓语动词的动作之前，用 动名词完成式。 She apologized to me for having kept me waiting for such a long time. 注意： after / before / on 后面的动名词不用完成 时态。 e.g） On hearing the news that we won the game, we were all wild with joy. He closed all the windows before leaving.
直接作主语
Teaching is my full-time job. Writing an English composition is not easy. 有时为了避免句子主语冗长，通常用it代替 v-ing作主语
It’s useless taking this kind of medicine.
Cleaning the windows is your task.
What I hate most is being laughed at.
Being laughed at is what I hate most.
•表语动名词与主语通常是对等的关系，表示 主语的内容，主语、表语可互换位置。
To see is to believe. Seeing is believing.
动名词—名词；习惯性动作 不定式—将来；一次性动作 现在分词: 动作正在进行；表主动 过去分词: 动作已经完成；表被动
﹡一般式：
不定式表示的动作与谓语动词表 示的动作同时发生，或者在谓语 动词表示的动作之后发生。
I’m glad to see you. (同时发生) They invited us to come to a party.（不定式动作后发生）
动名词作主语的形式主语句型
1.It is no use /good doing…. 2.It is not any use/good doing…. 3.It is worthwhile doing…. 4.It is hardly worth doing…. 5.There is no doing…. 6.It’s a waste of time doing…. E.g. It’s no good telling her all the truth. It’s no use crying over the spilt milk. There is no talking what will happen. It’s a waste of time arguing about it. It is worthwhile trying this experiment.
She came here to study English.
ห้องสมุดไป่ตู้
定语
状语
I warned the patient not to eat cold water after the operation. 宾补
兼具动词和名词的两种特征：动词有时态语态，有 宾语；名词有所有格，可以做主宾语，表语等等。 Helping him gave me a sense of pride. His house was damaged in the fire. My smoking caused this terrible fire. My parents dislike me/my smoking.
、功能及用法
1．动名词（短语）做主语，谓语用单数．如： Writing the book has taken up all his spare time. Judging people by his appearance is silly. 注：动名词作主语与不定式作主语的区别：
1) 动名词作主语往往泛指比较抽象的一般行为，如爱好、习惯等；
一.结构 : to do (否定) not/never to do 二. 时态与语态 不定式 主动语态
被动语态
to be done
----------
一般式 进行式
完成式
to do to be doing
完成进行式
to have been to have done done to have been ---------doing
动名词能在句中充当什么成分？
性质 主语 表语 宾语 宾补 定语 状语 动名 n. pron. 词
五、动名词的复合结构
动名词的复合结构就是前面带有代词或名词的动名词结构。 She won’t hear of us leaving the village. Do you object to Li Ping’s joining the physics group? 注①：逻辑主语是有生命的名词：作主语时，必须用名词或代词所 有格；作宾语时，也可用名词的普通格或人称代词宾格，如： The student’s knowing English well helped him in learning French. I don’t mind my / me / Jane buying another one. 注②：如果动名词的逻辑主语是表示无生命的东西的名词，或不定 代词，就只能用普通格，不能用所有格，如： Is there any hope of your team winning the match? The boy was alarmed by someone knocking at the door.