动词不定式和动名词一、动词不定式用法动词不定式没有人称和数的变化，在句中不能独立作谓语。

但动词不定式具有名词、形容词和副词特征，在句中可以作主语、宾语、宾语补足语、定语、表语和状语等多种成分。

另外，动词不定式具有动词特点，可以有自己的宾语和状语，组成动词不定式短语。

动词不定式的肯定形式是to＋do；其否定形式是not to＋do。

下面以动词不定式在句中的作用来予以详细说明。

1．作主语可以直接作主语。

如：To see is to believe．(1)但在英语中，常用it作形式主语，真正的主语即动词不定式放在后面。

如：It's wrong to play tricks on other people．It's our duty to keep our environment clean and tidy．点击规律：动词不定式在句中作主语时，常放在It is ＋adj．（形容词）＋to do sth．或It is ＋n．（名词）＋to do sth．句型中，it仅作形式主语。

(2)如果要表示不定式动作的执行者，就在It + be +形容词+to do sth该句型中的不定式之前加for sb或of sb。

①在形容词hard, difficult, easy, necessary, important, impossible, good, helpful, useful, dangerous, safe等之后常用for sb，即构成句型：It + be + 形容词+for sb to do sth。

e.g. I t’s not easy for us to learn a foreign language well.It’s dangerous for you to swim in the river.该句型中的形容词修饰的是不定式，强调的是做某事怎么样。

②在形容词nice, kind, clever, foolish(愚蠢的), polite(有礼貌的), careless, careful等之后，常用of sb，即构成句型：It + be + 形容词+of sb + to do sth e.g. It is very kind of you to help me. It was wrong of them to cut the trees.该句型中的形容词主要修饰人，表示某人的性质或特征，强调的是这个人怎么样。

(3)it作形式主语时，其后的谓语也可以是实义动词。

e.g. It took us five hours to get there. It made me happy to find my friends there.(4)动词不定式与疑问词how, what, when, where, which等构成不定式短语，也可作主语。

e.g. How to use the computer is the question. Where to go has not been decided.注意：主语，表语都为动词不定式时，不能用形式主语it代替不定式。

e.g. To see is to believe. 眼见为实。

2．作宾语a．want，decide ，agree等动词后面跟并且只能跟不定式。

如We agreed to start early．She wants to be a doctor．b．love，like ，begin，start，hate ，prefer等词后面可以接不定式。

点击规律：上述动词后面除接不定式外，还可以接动名词，意思无很大区别。

提示板：like doing指经常性动作，而like to do指一次性的动作。

如：I like swimming，but I don't like to swim now．我喜欢游泳，但我现在不想游。

c．stop，forget，remember，go on ，try等词或短语后面可以接不定式。

点击规律：上述动词后面接不定式和接动名词意思大不相同。

提示板：1）stop to do sth．：停止一件事，去做另一件事。

stop doing sth．：停止正在做的事。

例句：When the teacher came in，the students stopped talking；when he came out，the students stopped to talk．当老师走进来时，学生们停止说话；当老师走出去时，学生们又开始说话。

2）思考：forget，remember，go on，try等词或短语后面接不定式和动名词用法有何区别d．在find／feel＋it＋adj．＋to do sth．句型中，it是形式宾语，真正的宾语是后面的动词不定式。

如：The man downstairs found it difficult to get to sleep．I feel it easy to recite the text．点击规律：某些动词或短语后面既可以接动词不定式作宾语，又可接动名词作宾语，二者用法上的区别可以通过造句子加以区分，如上面stop例句。

3．作宾语补足语a．tell，ask，want，order，teach，invite，warn，wish，help，get，wish，help等词后面常接不定式作宾补。

如I tell him not to go there by bus ．Edison's mother taught him to read and write．b．let，make，have，see，hear，feel，watch，notice后面接不带to的不定式作宾补。

如：The boss makes them work 16 hours a day．I heard her sing in the next room．提示板：若变成被动语态，在上述结构中，不定式符号to要加上。

如：They are made to work 16 hours a day by the boss．She was heard to sing in the next room．4．作定语：放在被修饰的名词、代词后面例句：I have a lot of work to do.The doctor said he could do nothing to help the boy．点击规律：动词不定式若在句中作定语，常放在被修饰的名词、代词之后。

提示板：如果动词不定式和前面所修饰的词构成动宾关系，若动词是不及物动词，切记不要忘掉介词。

如：I have a small bedroom to live in．Have you got some pens to write with？5．表语：放在连系动词be后面例句：His wish is to become a scientist．The first important thing is to save the soldiers' lives．点击规律：动词不定式在句中作表语时，通常对连系动词前面的名词进行诠释说明。

6．作状语a．目的状语：放在go，come，use，live，in order等词后面。

如I come to see you．He runs fast in order to get there in time．b．原因状语：放在sorry，glad，surprised，disappointed，excited等词后面。

如I am glad to see you here．I am sorry to trouble you．c．作结果状语。

如：Some of the apples are hard to reach．The room is large enough to hold 1000 people．7．与what，who，whose，when，where，how等疑问词连用，作宾语、宾语补足语、主语等。

如：I don't know what to do next．（宾语）He taught us how to use the computer．（宾语补足语）It's still a question how to get there．（主语）二、动名词的用法动名词是动词的一种非谓语形式，由动词+ ing构成，否定形式为not doing，具有动词和名词的性质，在句中起名词作用，可作主语、宾语、表语和定语。

1.作主语动名词是由动词变化而来，所以，动名词的意义往往是表示某个动作或某件事情。

例如：Walking is good exercise. Seeing is believing. Smoking may cause cancer. Coming to Hangzhou by train takes about 16 hours. Swimming develops the muscles.动名词作主语时，对于一些比较长的动名词短语，一般采用"It is …"和"There is …"两种句式来表示。

例如： It's nice talking with you. It's no use arguing with him. It is no good learning without practice. It is worthwhile consulting your tutor about it again. There is no joking about such matters. There is no harm in doing so.2、作定语动名词作定语的情况并不是很普遍，一般只限于单个的动名词作定语，表示“用于……的”或表示“处于某件事情中的……”含义。

例如： swimming pool 游泳池 reading material 阅读材料walking stick 手杖opening speech 开幕词listening aid 助听器running water 自来水developing countries 发展中国家working people 劳动人民sleeping child 熟睡孩子当分词短语做后置定语时，可以转换成定语从句。

例：She went on board the train leaving for Shanghai. = She went on board the train, which was leaving for Shanghai. There are two roads before us, one leading to the beach, the other to the park.= There are two roads before us, one which leads to the beach, the other to the park.3、作表语动名词作表语的时候，特别要注意：不要与正在进行时混淆。