非限定动词即非谓语动词，是那些不能单独作谓语，在人称和数方面不受主语限定的，具有名词、形容词 和副词的某些特征的动词形式，是不定式、分词和动名词的总称。要想掌握非限定动词，首先要熟悉英语的句 子成分、时态及语态等，然后再了解非限定动词的特点、形式、作用及区别等。当然还要做些相关的习题。要 着重掌握以下内容。
    一.非限定动词的否定
    not须加在非限定动词之前。加强语气时用never代替not。
    1. 不定式的否定形式：I promised not to be late. You'dbetter not say that again.
    2.动名词的否定形式：Please excuse his not writing to you.
    3.分词的否定形式：Not having done his job, he is notallowed to go out.
    4.强调时的否定形式：Though never defeated in battle, theyfinally surrendered.
    二.非限定动词的完成式、进行式完成进行式及被动式
    1.完成式表示动作已经（或本应）完成，往往强调其动作发生在谓语动词的动作之前。
    I'm sorry to have woken you up.
    He intended to have come yesterday.
    Having failed twice, he didn't want to try again.
    2.进行式表示动作正在进行（或反复发生），有时强调某种情感。
    I pretended to be reading the newspaper.
    I don't want you to be forever finding fault with me.
    3.完成进行式表示动作一直在进行（或反复发生，往往与表示一段时间的状语连用。
    Having been standing the whole morning,I felt so tired.
    I'm sorry to have been troubling you all the time.
    4.非限定动词的逻辑主语是其动作的承受者时，要用相应的被动式。
    I want this to be done again.
    I object to being criticised so stupidly.
    The letter written by Tom was funny.（过去分词只有一般式，但自身有被动意义。）
    三. 主动式表示被动意义的用法
    1.动名词用于need, require, want（需要），demand 以及deserve之后要用主动式。
    My bike needs repairing. = My bike needs to be repaired.
    2.动名词用于worth之后要用主动式。
    The book is worth reading.
    3.动名词在past（超过）、for（适合于）、beyond （超过）等介词后要用主动式。
    Those trousers are past mending.
    This is a room for sleeping in.
    4.当不定式作定语，主语又是不定式的动作执行者时，能常用主动式。
    I have letters to write.我要写几封信。（我写—主谓关系）
    5.当不定式作表语，主语又是不定式的动作承受者时，通常用主动式。
    The book is easy to read.= It is easy to read the book. （读书—动宾关系）
    四、不定式不带to的用法
    1.不定式用于Why和Why not 之后不带to。
    Why spend so much money?
    Why not ask Susan to help you?
    2.当介词except、but前有do、did、does 时， 其后的不定式不带to。
    Can't you do anything but ask silly questions?（有do，无to）
    试比较：There's nothing to do but wait.
    There's no choice but to wait.（无do，需要to）
    3.不定式在had better／rather 、 would rather／sooner, rather／sooner than等短语后不带to。
    You'd better try again.
    I'd rather be told the truth than be lied to.
    4.不定式作have、make、let、feel、see、watch、notice、 hear、listen to、look at等动词（短语） 的宾语补足式不带to，作主语补足语时（即被动语态之后）则要带to。
    Her parents wouldn't let her go out alone.
    I heard him say that he was tired.
    试比较：He made me move my car.（作宾语补足语）
    I was made to move my car.（作主语补足语）
    五.不定式的几种用法
    1.有些名词要用不定式作定语。如need、decision、right、way、wish等。
    You did right to tell me the truth.
    He expressed a wish to be alone.
    2.名词或代词前有best、only、next、last、first时， 要用不定式作定语。
    I was the only one to arrive on time.
    He's always the first (person) to come and the last toleave.
    3.不定式可与whether或疑问句（why除外）构成复合式，作宾语、主语、表语和同位语。
    He'll tell you what to do.（作宾语）
    When to start is undecided.（作主语）
    4.进行时后面可跟不定式，却不能跟动名词。
    It's starting to rain.
    I'm going to tell you a story.
    5.有些动词（短语）要用不定式作宾语或宾语补足语。如hope，decide，expect，manage等。
    He hoped to win the contest.（宾语）
    注意：不定式不能作hope和suggest的宾语补足语。
    We wanted the dinner to taste good.（宾语补足语）
    六.动名词的几种用法
    1.介词（except，but除外）后面要用动名词。 尤其要注意介词to。
    What about sending her a postcard?
    I'm looking forward to seeing Ann.
    2.有些动词（短语）要用动名词作宾语。如：avoid、enjoy、finish、mind、suggest等。
    He dislikes seeing you with me.
    Paula has given up smoking.
    3.有些句型要求用动名词。 如there's nothing worse than,there's no, have（no）difficulty（或 trouble），what's the use（或point），have a hard time, be busy等。
    It's no use worrying.
    This clock is hardly worth repairing.
    试比较：I had difficulty finding it.
    It was difficult for me to find it.
    4.动名词前可用名词或代词作其逻辑主语，在句首用属格，不定代词或短语用通格。
    Do you mind my smoking?（在非正式场合可用宾格me 取代属格my）
    George's（或His）making fun of people got him into serious trouble.（属格）
    I can't imagine Frank and Mabel paying so much for apiano.（通格）
    七.分词的几种用法
    1.现在分词通常表示主动或进行的意义，过去分词通常表示被动或完成的意义。
    I found the man standing at the door.（正站着—主动）
    The man injured by the bullet was taken to hospital.（已受伤—被动）
    2.当主语是分词的动作执行者时，用现在分词；若是承受者时，则是过去分词。
    Sitting here, I can see the hills.
    Seen from here, the tower is tall.
    3.分词作表语时，表示特性用现在分词，表示状态用过去分词。
    The news was surprising. We were surprised at the news.
    4.“名词（代词的宾格）＋分词”称作“独立主格结构”，其作用相当于状语从句。
    It being Sunday, the library was closed.（相当于As it wasSunday......）
    八.非限定动词的用法辨析
    1.当宾语是补足语的行为执行者时，强调动作已完成不定式，强调动作在进行或将出现用现在分词；若是 承受者时，则用过去分词。
    We saw him leave the house.（已走出）
    She noticed him waiting there.（正在等）
    He had me swimming in a week.（去游泳）
    I heard her praised then.（受表扬）
    2.有些动词的空语要用动名词，宾语补足语却要不定式。 如admit、advise、allow、authorise、encour age 、 forbid 、 permit 、recommend等。
    We don't allow smoking in our house.（用动名词作宾语）
    He doesn't allow me to use the telephone. （用不定式作宾语补足语）
    3.有些词（组）后面要跟不定式，有些则要跟动名词。试比较：
    I would like to see that film.
    Do you feel like going out?
    The letter failed to arrive.
    He succeeded in solving the mystery.
    It took hours (for her) to get it.
    He spent hours reading last night.
    4.有些词（组）后面既可跟不定式，又可跟动名词，但含意不同。如remember、mean、learn等。
    I now regret saying what I said.（后悔）
    We regret to inform you that we are unable to offer youthe job.（抱歉）
    The minister went on talking for two hours.（连续）
    Having explained the theory, he went on to show us how todo it.（接着）
    5.有些搭配容易混淆。试比较：
    To teach is to learn twice.(To do...is to do...)
    Teaching is learning twice.(Doing...is doing...)
    I prefer driving to travelling by train.(prefer doing...to doing...)
    I prefer to drive rather than travel by train.(prefer todo...than do...)
    I would prefer to drive there.(would prefer to do...)
    I used to live alone.（sb. used to do...某人过去常常...）
    The cloth is used to clean the desk.（被动语态）
    She is used to driving on the left.（used 可换成accustomed习惯于...）