按照使用功能划分句子(一) 陈述句用于陈述事实和观点的句子叫陈述句。陈述句分为肯定结构和否定结构，句末用句号，一般用降调来读。例如：It is a shame that the local government is doing all it can to cover up what happened.当地政府正在竭尽全力掩盖事实真相，这真丢人。Jane can sing and dance.简能歌善舞。People dont dare to help when the old fall down on the street in that place.在那个地方，老人在街上跌倒了没人敢帮。James doesnt have a friend in the small town.詹姆斯在这个小镇里没有朋友。1.肯定陈述句在理解和运用肯定句时，要注意交际过程中，人们有时需要加强肯定的语气，强调方法有以下几种：(1)增添表示强调的副词或介词短语例如：Many people will certainly lose their jobs if the central government allows iron and steel companies to reduce capacity by shutting down plants.如果中央政府允许钢铁公司通过关闭工厂减少产能，许多人将会丢掉工作。The embassy staff are willing to do, without question, any favour that their own citizens may ask them.毫无疑问，使馆工作人员乐意对其本国公民可能提出的任何要求尽力提供帮助。(2)重复部分词语例如：Joan has realized her mistake, she has. 琼意识到自己的错误，她已经意识到了。I misunderstood your intentions, I did.我误会了你的意图，真的。Watch out for your business partner.He is an old fox, he is. 防着点儿你的生意伙伴，他是只老狐狸，真是。(3)运用双重否定，含蓄地加强肯定语气例如：Not a resident has access to the residential district without punching his card.业主不刷卡就进不了住宅小区。If the government cannot control the situation, military intervention is not impossible.如果政府无法控制局势，军事干预不是不可能的。You cannot make egg rolls without breaking eggs.有失才有得。(4)采用否定疑问句例如：Dont you know me,the once-Venus of our class sitting behind you?难道你不认识我了，那个坐在你后面的曾经的班花？Who doesnt know Barbara, the social butterfly in the town?谁不知道巴巴拉，小镇上的交际花？(5)主要动词前加do，并且重读do例如：Do believe me.I didnt tell a lie.一定要相信我，我没有说谎。I did meet Mike,having been to Miami for many years, on the street this morning. 今天上午，我的确在街上碰见了迈克，他搬到迈阿密很多年了。(6)采用重音转移的方式表强调例如：He was a fashion designer ten year ago. (He really was.)十年以前，他的确是一名服装设计师。I am telling you how the South Korean ferry sank on Thursday, April 24. (You must believe me.)我是在告诉你韩国客轮4月24日星期四如何沉没的。His backpack is full of food and drinks. (Not mine.)他的背包里装满了食物和饮料。2.否定陈述句否定陈述句的形式如下：(1)一般否定句一般否定句采用“主语+助动词/情态动词/be+not”形式。例如：The secretary has not finished typing the directors speech.秘书还没有打完主任的讲话稿。Those air hostesses in red uniforms are not from India.那些穿红色制服的空姐不是印度人。The lady from Quebec of Canada cant speak English very well.那位来自加拿大魁北克的女士不会讲流利的英语。【注释】not除了用来否定谓语动词，也可以用来否定句子中的其他词语，表示局部否定，不构成否定句。例如：He showed me around his farm not long ago.他不久前带我参观了他的农场。(否定副词词组)They said it not to me but to you.他们是说给我听的，不是说给你听的。(否定介词短语)(2)部分否定句部分否定句包括以下形式：not + all/both/every/everybody/everything等作主语句型，all/both/every/everybody等作主语的否定句，many/always/much/entirely等+not句型。例如：Not all that glitters is gold.(=All is not gold that glitters.)发光的并不都是金子。Everybody in his class wouldnt like Professor Dills lessons. (=Not everybody in his class would like Professor Dills lessons.)并不是班上所有的学生都喜欢迪尔教授的课。There are not many teachers in the school getting along well with Miss Lake.学校里和莱克女士关系融洽的并不多。She was not entirely satisfied with what her mother said.她对妈妈的话并不感到十分满意。Not very often did Allen go shopping although there was a supermarket nearby. (=Allen did not go shopping very often although there was a supermarket nearby.)尽管附近有一家超市，艾伦不经常去购物。(3)其他否定副词或代词构成的否定句这些词包括no、seldom、rarely、never、hardly、little、few、none、neither、nobody等。例如：He made no attempt to hide his displeasure at his daughters decision. 他没有掩饰自己对女儿决定的不快。No one is willing to employ someone who badmouths their previous employer.没有人愿意雇佣说前雇主坏话的人。She was never late for school when she studied in Dewey High School.她在杜威高中上学时从未迟到过。Mr. Johnson rarely greets his colleagues on his own initiative.约翰逊先生很少主动和同事们打招呼。These words and phrases are seldom used on ordinary occasions. 这些词语平时很少用。My nephew has two schoolbags but neither fits him properly.我侄子有两个书包，但是对他都不适合。None of the offices on the third floor are vacant.四楼没有办公室空着。(二)祈使句用来表示请求、命令、建议、劝告、警告等的句子叫祈使句。祈使句常以原形动词开头，句末一般用感叹号，语气较弱的祈使句句末可以用句号，通常用降调。祈使句的形式有以下几种：1.肯定祈使句祈使句的肯定结构是句首用动词原形，句前或句后可加please使语气更加委婉。例如：Be patient to your kids!对孩子要和善！(劝告)Keep off alcohol before driving!开车前不要饮酒！(警告)Pay attention, or youll miss the language points.注意，不然你会错过这些语言点的。(劝告)Give blood if you can and many lives will be saved.如果你能，来献血吧，这会挽救很多人的生命。(号召)【注释】“Do+祈使句”用于加强语气，意思是“务必，一定”。例如：Do be careful when crossing the street.过马路时一定要小心。Do give my regards to your parents,please!请务必代我向你的父母问好！2.否定祈使句祈使句的否定结构一般是在谓语动词前加do not，口语中用dont，有时也可以用never，如果祈使句有主语，否定词不可用do not。例如：Dont lean out of the window while taking a bus!乘坐公交汽车时不要把头伸出窗外。Dont you ever behave like that!不要那样做了！Never tell a lie again！别再说谎了！3. let祈使句Lets引导的祈使句，包括听、说者双方，表示建议，相当于“I suggest that you and I.”；Let me/us/him/her/it/them祈使句表示请求对方允许我方或第三方做某事，不包括对方在内，let相当于allow；let祈使句的否定式为“Lets not和Let me/us not”，但let him等第三人称否定式为“Dont let him”。例如：Lets drink to the friendship of our two nations!让我们为两国人民的友谊干杯！Lets do the job and try to finish it before noon.咱们现在就做这项工作，并且中午前干完。Let me decide the place and the time by myself!让我自己定地点和时间吧！Let us tell you the