新概念英语第一册语法知识点之情态动词的使用can, must, may, might, need情态动词can(能够)，must(必须)，may(可以) 结构：主语+can/must/may+动词原型He can make the tea.Sally can air the room.We can speak English.★变疑问句将情态动词移到句首Can he make the tea?Can Sally air the room?Can we speak English?★变否定句在情态动词后面加notHe cannot make the tea.Sally cannot air the room.We cannot speak English.★肯定回答及否定回答Yes, he can. No, he cannot.Yes, she can. No, she cannot.Yes, we can. No, we cannot.★特殊疑问句：What can you do?(必背)注意：情态动词的句子没有第三人称单数的变化，不要在情态动词或动词后面加S。
1)Must/have to的区别must 表示必须，是主观上觉得应该做，have to是不得不，是由于客观条件逼迫的必要要做must 只能用在表示现在和将来的句子里，而have to do可以用在任何时态2)must, may, might表示猜测：must do 表示对现在事实的猜测must have done表示对过去事实的猜测must have been doing 表示对过去正在进行的事实的猜测may/might do, may/might have done表示没有任何事实依据的猜测，might的可能性更小。
can’t/couldn’t 表示不可能新概念第一册语法讲解：一般现在时1、含有be动词的句子He is a teacher.The girl is very beautiful.Tim and Jack are students.★变疑问句将be动词移到句首Is he a teacher?Is the girl very beautiful?Are Tim and Jack students?★变否定句在be动词后面加notHe is not a teacher.The girl is not very beautiful.Tim and Jack are not students.★肯定回答及否定回答Yes, he is. / No, he is not.Yes, she is. / No, she is not.Yes, they are. / No, they are not.2、不含有be动词的句子，即含有一般动词的句子。
(1)第三人称单数及单数名词He likes books.She likes him.The dog likes bones.★变疑问句在句首加does, 动词变为原型Does he like books?Does she like him?Does the dog like bones?★变否定句在主语及动词之间加doesn't, 动词变为原型，原句中的动词不再有第三人称变化。
He doesn't like books.She doesn't like him.The dog doesn't like bones.★肯定回答及否定回答：Yes, he does. / No, he doesn't.Yes, she does. / No, she doesn'tYes, it does. / No, it doesn't.注意：第三人称单数形式一般在动词后面加S，不要和名词复数混淆，变否定句或疑问句时名词复数没有任何变化。
(2)其他人称及复数名词I want to have a bath.We have some meat.The students like smart teachers.★变疑问句在句首加doDo you want to have a bath?Do we have any meat?Do the students like smart teachers?★变否定句在主语和动词之间加don't.You don't want to have a bath.We don't have any meat.The students don't like smart teachers.★肯定回答及否定回答Yes, I do. / No, I don't.Yes, we do. / No, we don'tYes, they do. / No, they don't.新概念第一册语法讲解：现在完成时现在完成时构成：主语+助动词have, has+过去分词用法：1) 表示过去发生的和现在有某种联系的动作，常和just, usually, already, since等时间副词连用。
I have just had lunch. (饱了，不用再吃了。
)He has had a cup of tea.(不渴了，不用再喝。
)They have already had their holiday. (不能再度假了。
)The boy has already read the book. (已经知道书的内容了，不用再看了。
)2) 询问别人是否做过某事一般用现在完成时：Have you finished your homework?Have you been to Beijing?Have he seen the film?3) 表示开始于过去并持续到现在的动作I have lived in Beijing for twenty years.I have worked for this school for 1 year.4) 表示一种经历，经验：去过…地方，做过…事情，经历过…事情I have never had a bath.I have never seen a film.I have never been to cinema.I have ever been to Paris.Have been to表示去过，have gone to 表示去了I have been to London.(人已经回来)He has gone to London.(人还在那里)5) 表示一种结果，一般不和时间副词联用I have lost my pen.I have hurt myself.He has become a teacher.She has broken my heart.句型变化：★变疑问句将助动词移到句首，变否定句在助动词后面加not.Have you lost your pen? I have not lost my pen.★肯定回答及否定回答Yes, I have. / No, I have not.★特殊疑问句What have you done?What has he done?一般过去时与现在完成时的区别：凡是有明确的表示过去的时间状语的句子为过去时。
注意：有些动词表示的动作有一个终点，不能再延续，因此不能和表示一段时间状语连用。
错：I’ve left Beijing for 3 days.对：I left Beijing 3 days ago. I have been away from being for 3 days.新概念英语第一册语法知识点：定语从句定语从句1.了解定语从句的构成，首先应了解一些相关的基本概念。
a.被修饰的名词等成分通常叫做先行词;b.连接先行词和定语从句的词为关系词。
2.定语从句由关系代词、关系副词和关系限定词三类关系词连接而成，这三种也将在定语从句讲解中一一说明。
定语从句讲解关系词的具体用法1.关系代词which，who，whom，that 和as2.关系代词，顾名思义，必有代替对象。
上述五个关系代词各有其具体指代对象，在从句中作相应的成分。
此外，它们引导的定语从句和先行词是形容词与名词的修饰关系。
例句及翻译例句1:Pumas are large，cat-like animals( that/which are found in America.)【译文】美洲狮是体形似猫的大型动物，产于美洲。
【注解】关系代词作从句主语，不可省略。
例句2:The house (that/which we built last year) is very attractive.【译文】我们去年建造的房子很讨人喜欢。
【注解】关系代词作从句宾语，可省略。
例句3:The novel (with/which most of you are familiar) has been adapted for thescreen.【译文】你们大多数都很熟悉的那部小说已被改编搬上了荧屏。
【注解】关系代词直接置于介词后作介词宾语，此时不可被that替换，也不可省略。
例句4:He was no longer the reckless young man( that/which he was two yearsago).【译文】他不再是两年前那个莽撞的小伙子了。
【注解】关系代词作从句表语，可省略;此外，先行词the young man代表一种状态，属物的范畴，不能用who来引导定语从句。
例句5:Migrant workers(to whom much more attention has been paid) strongly desirethat their wages should be duly paid.【译文】现在民工受到了社会更大的关注，他们强烈渴望自己的工资能够及时发放。
【注解】关系代词直接置于介词后作介词宾语，此时不可被who替换，也不可省略。
例句6:Such accommodations(as they could find) were generally expensive.【译文】他们能够找到的这些住所费用往往比较昂贵。
【注解】之所以选择关系代词as引导定语从句，是因为前面有such之故。
例句7:Such inns(as there were in the mountains) were generally poor.【译文】这些山区里的酒馆条件往往比较糟糕。
【注解】之所以选择关系代词as引导定语从句，是因为前面有such之故。