语法讲座与练习（一）非谓语动词在句子中充当除谓语以外的句子成分的动词形式叫做非谓语动词。
非谓语动动词不定式（the Infinitive）动词不定式由to+动词原形构成。
这里的to是不定式标志，没有词义。
不定式具有名词、形容词或副词的某些语法功能，又有动词的时态和语态的特点及作用。
1．不定式作主语To say something is one thing, but to do it is another.[注]不定式作主语，尤其是当主语较长而谓语较短时，往往用it作形式主语，真正的主语不定式放至句子的后面。
例如：It's so nice to hear your voice.It's necessary for you to lock the car when you do not use it.It seemed selfish of him not to give them anything.典型例题The chair looks rather hard, but in fact it is very comfortable to ___.A. sitB. sit onC. be seatD. be sat on答案：B. 如果不定式为不及物动词，其后应有必要的介词。
2.不定式作宾语，大致上有三种情况。
1）有些及物动词用不定式作宾语，结构为动词+不定式。
例如：afford aim agree arrange ask attempt bother care choose claim consent determine decide decline demand desire determine expect elect endeavor hope fail help learnlong 渴望mean manage offer plan pretend refuse tend undertake volunteer seek intend promise threaten prepare例如：The driver failed to see the other car in time.He offered to help me.2）有些动词或动词词组可以用动词+疑问词+不定式的结构作宾语。
例如：decide know consider forget learn remember show wonder find out tell inquire explain 例如：Please show us how to do that.There are so many kinds of tape-recorders on sale that I can't make up my mind which to buy.疑问词+不定式的结构也可做主语和宾补.3) 有些动词可以跟there +to be的结构。
例如：believe expect intend like love mean prefer want wish understand例如：We didn't expect there to be so many people there.You wouldn’t want there to be another war.3. 不定式作补语1）有些有动词+宾语+不定式的结构。
例如：advise allow cause challenge command compel drive 驱使enable encourage forbid force impel induce instruct invite like/love order permit make let permit want get warn persuade request send tell train urge inspire warn teach want ask expect 例如；Father will not allow us to play on the street.The officer ordered his men to fire.注意：感官动词see，hear，observe，watch，notice，feel等和使意动词如make，have，let，用不定式作做宾补要省略to,但作为主补不定式带to.例如：The teacher makes us write a composition every week.We are made to write a composition every week.2) 有些有动词+宾语+不定式的结构，不定式的动词往往是be，不定式一般可以省去。
例如：appoint consider find believe think declare（声称）guess fancy（设guess judge imagine know 想）例如：We believe him to be guilty. 我们相信他是有罪的。
We know him to be a fool. 我们知道他是个笨蛋。
（to be 不能省去）典型例题Charles Babbage is generally considered___ the first computer.A. to inventB. inventingC. to have inventedD. having invented答案：C. 一般没有consider+宾语+be以外不定式的结构，也没有consider+宾语+doing的结构，排除A、B、D。
consider用动词be以外的不定式作宾补时，一般要求用不定式的完成式，故选C。
4. 不定式作表语不定式可放在be动词后面，形成表语。
例如：My work is to clean the room every day.The question is how to organize the work.To see is to believe.5. 不定式作定语不定式做定语通常要放在被修饰的词后，往往表示未发生的动作。
例如：I have a lot of work to do.There was nothing to bring home that morning.常跟不定式做定语的名词中，有很多是有常跟不定式的动词或形容词派生来的,常见的有ability, agreement, ambition, anxiety, attempt, claim, decision , determination, eagerness, failure, intension, hope, plan, promise, refusal, reluctance, resolution, tendency, threat, wish等.例如:His attempt to sole the problem failed again.The first, second, last, only best等后可跟不定式做定语。
例如:He is always the first to come and the last to leave.6. 不定式作状语1）目的状语常用结构为to do , only to do（仅仅为了）, in order to do,so as to do,so （such）… as to…（如此…以便…）。
例如：He ran so fast as to catch the first bus.I come here only to say good-bye to you.2）作结果状语，可以表示没有预料到的或事与愿违的结果，不定式要放在句子后面。
I awoke to find my truck gone.He searched the room only to find nothing.3）表原因I'm glad to see you.She wept to see the sight.4）做独立成份To be fair, he has worked hard these days.We don’t like your idea, to tell you the truth.7.作谓语结构的一部分1)be said /reported/ know…+不定式Shanxi Province is known to have rich coal reserves.2)be likely/ certain/ sure/ wi ling/ anxious, ready/ bound / eager/ reluctant… +不定式He is always ready to help others.几点注意事项1.不定式的逻辑主语不定式作主语和宾语时,当逻辑主语不是句子的主语时,要用for或of+名词/代词放在不定式前做逻辑主语.即 It's for sb. to do和It's of sb. to do1）for sb. 句型中的形容词一般为表示事物的特征特点，表示客观形式的形容词，如easy, hard, difficult, interesting, impossible等：例如：It's very hard for him to study two languages.2）of sb.句型中的形容词一般为表示性格，品德，心智能力，表示主观感情或态度的形容词，如absurd, bold, brave, careful, careless, clever, considerate, courageous, cruel, foolish, good, grateful, honest, kind, nice, polite, right, rude, silly, stupid, thoughtful, wicked, wise, wrong。
例如：It's very nice of you to help me.I think of him not to accept our invitation.2. 动词不定式的否定式在不定式标志to前加上not。
例如：Tell him not to shut the window。
She pretended not to see me when I passed by.典型例题1）Mrs. Smith warned her daughter ___ after drinking.A. never to driveB. to never driverC. never drivingD. never drive答案：A。