英语改错题

有需求/要求...

需要

过分要求的, 苛求的

你好！“要求严厉的”的英语单词是：Demanding或者是strict.比如：她是一位要求严厉的老师。She is a strict teacher.

与for 连用

质量要求高的工作吃力的工作

demanding是形容词，要求苛刻的，可以指人也可以指物。It"s a demanding job.He is a demanding teacher.

看看主语和上下文 主语是物用demanding

对工作要求严格be strict in one"s workHe is always strict in his work.他总是对工作要求很严格。

一直在等待直到眼泪留下来到最后一刻犯过的错没人会在意你过去的痛你的梦我一直都记得谁说我不懂最后的选择也许可能或许说不定多少年后还能在哪里相遇我一直在等待直到眼泪留下来就算如今分开你还是那么可爱认识你的秋天也许再也回不来等待等待等待有一个人能够代替你的离开（K-BO)想你的时候牵不到手(光光）babyIluvally"all4realbutiknowi"llloseuyepiknowboomqgqgboomqgqgboom记得动记得记得动记得你的梦不会放开手却不知道怎么样开口挥之不去的记忆太重要的地位该怎么继续那悲伤的气味还记得那年教室门口我和你拉的勾还记得这么多年以来我为你发的疯你假装当是解脱我听到你说回过头看这一路改变真的好多想牵你的手最后一次街边一起走虽然没有太多话说我却体会你的感受OHOH和我一样的感受OHOHOH因为早融入你的心你听你听你听你听（K-BO）想你的时候牵不到手，就这样不回头目送我就此远走离开这伤口又是这个秋天的时候离开你向前走却发现泪不停的流想你的时候牵不到手，就这样不回头目送我就此远走离开这伤口又是这个秋天的时候离开你向前走却发现泪不停的流（光光）iknowusaiddatitsovernowhowcanIbsodamndemanding，就这样不回头目送我就此远走离开这伤口又是这个秋天的时候离开你向前走却发现泪不停的流想你的时候牵不到手

1. 虽然肖邦的作品被认为是最难演奏的钢琴曲，但它们其实很注重的是微妙的情感和表达深度，而不仅仅是演奏技术的展示。demanding（苛求的，困难的） pieces （这里只曲子）ever created（曾被创作出的） for piano（为了钢琴演奏）：史上曾被创作出的最难的钢琴曲2.该机构报告说它通过严格执行国家规定，已经成功地将工业污染降至可以接受的水平。it指the agency ; enforcing(执行）的逻辑主语也是agency

主语 the young clerk， 谓语， expressed， full of confidence，副词that he was qualified for that demanding 宾语从句。这个年轻的员工充满信心的表示对那个苛求的（工作），他完全合格句子应该差了一个名词做从句的宾语，demanding只能做形容词或 动词ing 形式

劳神费力的职业

　　demanding post的中文翻译　　demanding post　　要求后　　双语例句　　1　　I would also like to convey my gratitude to your predecessors in this demanding post, who have shown remarkable devotion to the work of the Conference.　　我还愿意向您在这一要求很高的职位上的前任表示感谢，他们十分出色地献身于裁谈会的工作。　　2　　Before they get to that, there"s another hitch: Finland and some others are demanding that Greece post collateral in exchange for continued rescue lending.　　但在此之前还有一道障碍：芬兰和其它一些国家要求希腊提供抵押品以换取持续的援助贷款。

　　He wanted to resign because the boss is very picky, has been satisfied with his work.

如果特斯瑞特人也少有

A

Demanding career 全部释义和例句>>职业生涯求采纳祝您新春快乐

demand program 需求计划双语对照词典结果：网络释义1. 需求计划例句:1.Upgrades will be offered for the duration of the Troop Greetings On Demand program.2.These ads also telescope directly into the Hotel Deals On Demand program.

Demanding = 苛索 例句: She is a demanding person. 她是一个很苛索的人. high expectation 先系要求高 例句: I have very high expectation on you. 我对你有很高要求. NU There are many ways to express depend on "要求高" on what. 英文要求高: good mand of English Strong background on puter programming High proficiency on Speaking France demand high 参考: .dictionary.yahoo/search?s=demand gao ㄍㄠ 1.tall; high 2.of a superior grade or type 3.(of voice) high; loud 4.[Polite] your respected 参考: me 你可说: Requests high 2006-11-30 18:59:08 补充： 例句::He is very requests high to you.(他对你要求很高。) 参考: me

consider it rude and overly demanding认为这是粗鲁和过分的要求

搜狗输入法上有一个中英互换

嗯

demanding意思是高强度的，需要很大努力的

你所说的应该是属于现在分词和过去分词做定语而转化为形容词的问题。先说ING形容词，也就是现在分词做定语，有两种。一种已转化为形容词，已无动词性质，这种词不但可以被副词VERY修饰，而且也可以有比较的变化。另一种则仍有动词性质，不可被副词VERY做修饰，也没有比较的变化。试比较：a promising young man 一个有为的青年（已无动词性质）a leading comrade 领导同志（仍有动词性质）常见的已转化为形容词的现在分词有alarming,amusing,astonishing,charming,daring,demanding,encouraging,confusing,disappointing,discouraging,exciting,grasping,interesting,inviting,misleading,pleasing,promising,refreshing,revealing,shocking,striking,surprising等。多数现在分词并未转化为形容词，如:developing countryworking class一般来说，现在分词做定语时有动词性质，具有能动性。而形容词只表一种品质或性能。再说过去分词做定语。和现在分词一样，有些过去分词也已变作形容词。他们失去了动词的性质，所以可被副词VERY，TOO等所修饰，并可以有比较的等级，这种过去分词常见的有：advanced, aged, blessed, conceited, contented, crooked, cursed, disappointed, distinguished, excited, frightened, interested, learned, limited, pleased, pronounced, reserved, surprised, tired等。尚未转化成形容词的过去分词一般不可用副词VERY等修饰，但可以用副词MUCH修饰。还有一些过去分词虽然尚未转化成形容词，却也可以被副词VERY修饰。常见的有：alarmed, amazed, amused, balanced, bored, disturbed, divided, embarrassed, exhausted, fascinated, hurt, lined, puzzled, relaxed, satisfied, shocked,specialized, worried.现在分词与过去分词在意义上不同，一般来说，现在分词表主动、正在进行，过去分词表被动、已经完成。同学你完全可以找个老师进行补习啊！想英语学习效果有全面的提高,就要找一个专业的老师进行一对一的辅导。在奥维斯发展大厦29层就可以帮助你提高英语水平，那里中教一对一外教一对四一对八。相信你在那里学习会有明显提高。

要求过高的

这应该是一份资讯信息吧课程有固定的课程时间表吗？ 是的/不是 申请人要求是国际文凭候选人吗？ 是的/不是 如果你们提供AP课程，会限制学生选课数量吗？ 是的/不是 你们学校一共提供多少AP课程？ ________ 筹备与其他大学相比，在您的学校的学生，申请的课程选择是： “最苛刻 “非常苛刻 “苛刻“平均 “低于平均水平 大概就是这个意思 应该能看懂吧

Meaning of: [some water experts are now demanding that existing infrastructure be used in *** arter ways rather than building new facilities which is increasingly considered the option of last not first resort.] My opinion: The relative pronoun "which" in this sentence refers to the noun phrase "building new facilities". The pound noun "last resort" me the "last possible course of action". By contrast "first resort" me the action one would consider taking first. There are o options given in this sentence one option is to build new facilities as the first resort the other option is to build new facilities as the last resort. Therefore the whole sentence can be broken down into 3 sentences: 1. Some water expers are now demanding that existing infrastructure be used in *** arter ways rather than building new facilities.. 2. Building new facilities is increasingly not considered the option of first resort. 3. Building new facilities is increasingly considered the option of last resort. Once we take away the repetition the 3 sentences can be reconstructed to bee the original sentence. 2010-03-07 06:38:32 补充： 本来各答各的，互不相干。但不去指出与事实或真理完全相反的答案，亦是对知识+不负贵任的行为，所以不得不说： [Last resort] 解 [用尽了其它办法，最后迫不得已才会采用的辨法]。 绝对不是如 002 所说，解 [最终的解决办法]。 参考: myself 001 is absolutely correct. some water experts are now demanding (A) rather than (B) which is increasingly considered the option of last not first resort. which -----> B i.e. B is increasingly considered the option of last resort (not first resort.) thank you for you wer~ 答案够详尽！ 赞！ which is increasingly considered the option of last not first resort. 它 日益被视为最终的(解决办法) 并非初步的解决办法。 Which 是指 existing infrastructure be used in *** arter ways rather than building new facilities 2010-03-07 00:00:57 补充： "using existing infrastructure in *** arter ways" is the option of last resort

因为前面主语 客户 the client是单数啊。

“但人类心理的复杂性使管理成为微妙而有难度的艺术。”这里 a subtle and demanding art做宾语补足语，make是谓语，management是宾语，而a subtle and demanding art补充说明management的性质和情况。【公益慈善翻译团】真诚为您解答！

Teaching is a demanding career. Many people have the misconception that teaching is an easy task. After all, teachers have all the answers to the questions and can structure lessons in a manner that he or she deems fitting. However, people fail to see the hard work that teachers have to put in just to have a 30-minute lesson.Lesson planning and preparation is essential to a successful delivery of the lesson. Teachers spend so much time preparing and planning. Also, children nowadays are tougher to educate and discipline. Parents sometimes don"t always agree with the homework load or stress levels and blame it on teachers. If students don"t perform well, principals will also ask teachers to explain why. Thus, being a teacher is so demanding because you have to face pressure from all these parties.

The son of zeus and alcmene , a hero of extraordinary strength who won immortapty by performing 12 labors demanded by hera 宙斯和阿尔克墨涅之子，力大无比的英雄，因完成赫拉要求的十二项任务而获得永生。 Our key move of expanding labor demand and resolving rural employment is to bring about rural industriapzation , and to promote transfer of rural surplus labor 根据我国新农村建设的实际情况，扩大劳动力需求和解决农村就业问题的关键之举在于，走农村产业化道路，加快农村剩余劳动力的转移就业。 In the early , the culture has an important effect on the jvs which belong to high labor demanding industries , but in the upper phase , the technology resourses has more significant influence than the culture on those from high technology demanding industries 在中外合资企业发展的初期阶段,合资企业主要集中于劳动密集型行业,文化背景的影响非常显著,而到了中后期,合资企业向技术密集型行业转移,技术资源的影响显得更为重要,文化背景的影响力逐渐减弱。 Our study shows through economic channels ( reduction in labor demand , relative price change , fiscal retrenchment , changes in the value of assets , worsen of social environment ) , and via the channels of financial transfer which from non - participants to participants of the financial sector , financial crises and it " s resolution worsened the distribution of ine and poverty in ldcs 我们的研究显示：通过劳动要求的减少、商品相对价格的变化、公共支出的削减、实物与金融资产价格变化和社会环境的恶化等经济渠道，以及由非参与者到金融系统参与者的金融转移渠道，金融危机及其治理加重了发展中国家的贫困程度，恶化了收入分配状况。 Based on the research of anhui province , the basic conclusion of labor supply and demand of rural area in the construction of new rural area are as follows : labor supply is generally larger than labor demand ; the speed of economic growth is the decisive factor of the gap beeen labor supply and labor demand ; and the shortage of scientific and technical workers in the rural area will be the important characteristics 摘要本文基于安徽省的研究，得出关于我国新农村建设中的农村劳动力供求的基本结论是：劳动力供给总体上大于劳动力需求；经济增长的速度将成为决定劳动力供求缺口大小的决定性因素；农村地区还存在农村科技人员的劳动力短缺的特征。

歌曲名:When Doves Cry歌手:Prince专辑:Oe3 Zeitreise 1984When Doves CryDig if u will the pictureOf u and I engaged in a kissThe sweat of your body covers meCan u my darling--can u picture this?Dream if u canA courtyardAn ocean of violets in bloomAnimals strike curious posesThey feel the heatThe heat between me and uHow can you just leave me standing?Alone in a world that"s so coldMaybe I"m just 2 demandingMaybe I"m just like my father 2 boldMaybe you"re just like my motherShe"s never satisfiedWhy do we scream at each otherThis is what it sounds like when doves cry.Touch if you will my stomachFeel how it trembles insideYou"ve got the butterflies all tied upDon"t make me chase uEven doves have prideHow can u just leave me standing?Alone in a world so cold, world so coldMaybe I"m just 2 demandingMaybe I"m just like my father 2 boldMaybe you"re just like my motherShe"s never satisfiedWhy do we scream at each otherThis is what it sounds like when doves cry.How can u just leave me standing?Alone in a world so cold, world so coldMaybe I"m just 2 demandingMaybe I"m just like my father 2 boldMaybe you"re just like my motherShe"s never satisfiedWhy do we scream at each otherThis is what it sounds like when doves cry.edit morrison tsaihttp://music.baidu.com/song/60394993

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）フロアートンネルスチフナー2）车顶网站3）后部车架4）后面フロアー横梁5）烯轮机机宜6）前散装床7）前侧板8）前车轮住宅9）后车轮住宅10）中间フロアー横梁11）德アビーム12）前フロアー框架13）前界内米尔

问题一：我没时间用英语怎么说 你好 I have no time!!! 或者是 i am busy!!! 问题二：我没时间了 用英文怎么说 I haven"t got any time 问题三：英文中“没时间”怎么说 您好！ 以下资料供您参考，祝您开心每一天！ -------------------------------------------- don"t have time have no time 问题四：没时间用英语怎么翻译 time shortage 问题五：我没时间 英语怎么讲 I"m busy. I have no time. 希望能帮到你，祝更上一层楼O(∩_∩)O 问题六：“没时间理你“用英语怎么说？ rap to 搭理 I have no time rapping to畅you. 或者 I have no spare time for you. Don"t waste my time. 问题七：没钱没时间用英文怎么说 I have no money or time. 问题八：现在我没时间，英文怎么说？？？ Ihavenotimerightnow

1.yet还可用于转折3.B4.去掉the5.照片中是李明，照片中是我，属于我的照片

歌曲名:Love Me For What I Am歌手:Lobo专辑:The Best Of LoboLove me for what i amI wore the clothes you likedYou said they gave me that lookI even tried to like the foodI know you like to cookI parted my hair on the leftI carried your arm on the rightI slept late in the morningAnd I stayed out late at night.I can"t give any more of my soul awayAnd still look myself in the mirror everydayI can"t change any moreof what makes me be myselfAnd still have enough leftnot to be somebody elseI"m not demanding as a manJust asking you - love me for what I am.I tried hard not to saythe things you don"t like to hearAnd when to you it was aproposI nibbled on your earI opened the door up for youI kept my big mouth shutWell I"ve been going downWhile you"ve been going upI can"t give any more of my soul awayAnd still look myself in the mirror everydayI can"t change any moreof what makes me be myselfAnd still have enough leftnot to be somebody elseI"m not demanding as a manJust asking you - love me for what I amI can"t give any more of my soul awayAnd still look myself in the mirror everydayI can"t change any moreof what makes me be myselfAnd still have enough leftnot to be somebody elseI"m not demanding as a manJust asking you - love me for what I amoh~love me for what I amoh~love me for what I amhttp://music.baidu.com/song/54915444

答案是 A,being 现在分词的独立主格结构 作状语如果选D ，则是并列句，逗号后面须加and

Dig if you will the pictureOf you and I engaged in a kissThe sweat of your body covers meCan you my darlingCan you picture this?Dream if you can a courtyardAn ocean of violets in bloomAnimals strike curious posesThey feel the heatThe heat between me and youHow can you just leave me standing?Alone in a world that"s so cold? (So cold)Maybe I"m just too demandingMaybe I"m just like my father too boldMaybe you"re just like my motherShe"s never satisfied (She"s never satisfied)Why do we scream at each other?This is what it sounds like When doves cryTouch if you will my stomachFeel how it trembles insideYou"ve got the butterflies all tied upDon"t make me chase youEven doves have prideHow can you just leave me standing?Alone in a world so cold? (World so cold)Maybe I"m just too demandingMaybe I"m just like my father too boldMaybe you"re just like my motherShe"s never satisfied (She"s never satisfied)Why do we scream at each other?This is what it sounds like When doves cryHow can you just leave me standing?Alone in a world that"s so cold? (A world that"s so cold)Maybe I"m just too demanding (Maybe, maybe I"m like my father)Maybe I"m just like my father too bold (Ya know he"s too bold)Maybe you"re just like my mother (Maybe you"re just like my mother)She"s never satisfied (She"s never, never satisfied)Why do we scream at each other? (Why do we scream? Why?)This is what it sounds like When doves cryWhen doves cry (Doves cry, doves cry)When doves cry (Doves cry, doves cry)Don"t Cry (Don"t Cry)When doves cry When doves cry When doves cry When Doves cry (Doves cry, doves cry, doves cry)Don"t cryDarling don"t cryDon"t cryDon"t cry

select查询的是多个数据，返货的结果也是二维数组find是查询的一条数据，返回的是一维数组

dui

这个是莎士比亚戏剧《哈姆雷特》中的名句，全句是 To be, or not to be - that is the question 意思是说 活着还是死去，这是一个问题。 附相关章节： Hamlet"s endurance has reached the breaking point. His father has been murdered. His mother, who he loves dearly, has married her dead husband"s brother. Moreover his sweetheart, Ophelia, has been acting very strangely. He senses that she does not love him any more. Now, he"s all alone. The world that he knew is shattered. His black mood of despair is deepened by his inability to act - to do something to change the situation. Now he ponders whether to continue living - or to take his own life. Hamlet: To be, or not to be - that is the question: Whether "tis nobler in the mind to suffer The slings and arrows of outrageous fortune Or to take arms against a sea of troubles, And by opposing end them. To die - to sleep - No more; and by a sleep to say we end The heartache, and the thousand natural shocks That flesh is heir to. "Tis a consummation Devoutly to be wish"d. To die - to sleep. To sleep - perchance to dream: ay, there"s the rub! For in that sleep of death what dreams may come When we have shuffled off this mortal coil, Must give us pause. There"s the respect That makes calamity of so long life. For who would bear the whips and scorns of time, The oppressor"s wrong, the proud man"s contumely, The pangs of despised love, the law"s delay, The insolence of office, and the spurns That patient merit of the unworthy takes, When he himself might his quietus make With a bare bodkin? Who would these fardels bear, To grunt and sweat under a weary life, But that the dread of something after death - The undiscover"d country, from whose bourn No traveller returns - puzzles the will, And makes us rather bear those ills we have Than fly to others that we know not of? Thus conscience does make cowards of us all, And thus the native hue of resolution Is sicklied o"er with the pale cast of thought, And enterprises of great pith and moment With this regard their currents turn awry And lose the name of action.

current形容词currently是副词主要看修饰什么词

"""+typeld+""" 这里typeld是你程序中运算出来的，不是SQL里面的字段，是一个值

日食的一个食季是36天，这个天数比一个朔望月的平均长度29.53还要长。因此在一个日食的食季内必定会发生一次日食，也可能发生两次日食。一年之中有两个日食食季，所以在一年之内至少有两次日食发生，也可能有四次日食发生.今年8月1日有一次日全食，我国中西部地区都可以观测，而且条件不错，希望楼主可以关注。

https://pan.baidu.com/s/1UO5-JqQqL7BK3U6kNpAK2g?pwd=5naehttps://pan.baidu.com/s/1R-ZU0jwLcVkPvbvC3uhWdw?pwd=rqtx

select是动词，selection是名词。

更新1: 何博士﹕你个人看法认为无线输电这可能性大吗？我总觉得这么大的能量存在于大气中是有问题的，可能在这Tesla Coil 发射塔方圆数十里也要生人勿近！ 1.高电压电力装置测试仪器之一 所以需要超高电压来测试。 2.特斯拉线圈(Tesla Coil)是一种使用共振原理运作的变压器(共振变压器)，由美籍塞尔维亚科学家尼古拉特斯拉在1891年发明[1]，主要用来生产超高电压但低电流、高频率的交流电力。特斯拉线圈由两组（有时用三组）偶合的共振电路组成。特斯拉线圈难以界定，尼古拉特斯拉试行了大量的各种线圈的配置。特斯拉利用这些线圈进行创新实验，如电力照明，荧光光谱， X射线，高频率的交流电流现象，电疗和无线电力，以便进行电力传输。 3. 图片参考：upload.wikimedia/ *** /mons/f/fa/Lightning_simulator_questacon02 图片参考：upload.wikimedia/ *** /mons/thumb/f/fa/Lightning_simulator_questacon02/800px-Lightning_simulator_questacon02 upload.wikimedia/ *** /mons/f/fa/Lightning_simulator_questacon02 图片参考：upload.wikimedia/ *** /zh/7/78/Telsa_Coil_2 zh. *** /zh-/%E7%B4%85%E8%89%B2%E8%AD%A6%E6%88%92%E7%B3%BB%E5%88%97 2009-09-21 09:33:29 补充： 本来已经可以在世界安装既，因为有其他利益上既冲突，所以迟到家阵仲未实行安装，无线输送电流是一种突破性工艺，到时好多人冇工作啦。 2009-09-21 09:46:52 补充： 方法如下 在外太空建立一座太阳能发电站，再做特斯拉线圈由两组（有时用三组）将电源变换，又在地球上做接收器，或者在任何的地方包括家里，汽车，火车，轮船，飞机上都可以安装接收器，你就有免费电源用啦。 在外太空太阳是24小时供应的，也不怕发射塔方圆数十里也要生人勿近！ 在外太空也没有打雷的，也不必还税，不过多了一个向地球或宇宙发放辐射既特斯拉线圈，你要吗？

当一个节点和多个节点建立连接时，如何高效的处理多个连接的数据，下面具体分析两者的区别。1. select函数函数原型：int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);参数介绍：（1）nfds -- fdset集合中最大描述符值加1（2）fdset -- 一个位数组，其大小限制为_FD_SETSIZE(1024)位数组的每一位代表的是其对应的描述符是否需要被检查。（3）readfds -- 读事件文件描述符数组（4 ）writefds -- 写事件文件描述符数组（5）exceptfds -- 错误事件文件描述符数组（6）timeout -- 超时事件，该结构被内核修改，其值为超时剩余时间。对应内核：select对应于内核中的sys_select调用，sys_select首先将第二三四个参数指向的fd_set拷贝到内核，然后对每个被SET的描 述符调用进行poll，并记录在临时结果中（fdset），如果有事件发生，select会将临时结果写到用户空间并返回；当轮询一遍后没有任何事件发生时，如果指定了超时时间，则select会睡眠到超时，睡眠结束后再进行一次轮询，并将临时结果写到用户空间，然后返2. select/poll特点传统的select/poll每次调用都会线性扫描全部的集合，导致效率呈现线性下降。poll的执行分三部分：（1）.将用户传入的pollfd数组拷贝到内核空间，因为拷贝操作和数组长度相关，时间上这是一个O（n）操作（2）.查询每个文件描述符对应设备的状态，如果该设备尚未就绪，则在该设备的等待队列中加入一项并继续查询下一设备的状态。 查询完所有设备后如果没有一个设备就绪，这时则需要挂起当前进程等待，直到设备就绪或者超时。设备就绪后进程被通知继续运行，这时再次遍历所有设备，以查找就绪设备。这一步因为两次遍历所有设备，时间复杂度也是O（n），这里面不包括等待时间......（3）. 将获得的数据传送到用户空间并执行释放内存和剥离等待队列等善后工作，向用户空间拷贝数据与剥离等待队列等操作的的时间复杂度同样是O（n）。3. epoll机制Linux 2.6内核完全支持epoll。epoll的IO效率不随FD数目增加而线性下降。要使用epoll只需要这三个系统调用：epoll_create(2)， epoll_ctl(2)， epoll_wait(2)epoll用到的所有函数都是在头文件sys/epoll.h中声明的，内核实现中epoll是根据每个fd上面的callback函数实现的。只有"活跃"的socket才会主动的去调用 callback函数，其他idle状态socket则不会。如果所有的socket基本上都是活跃的---比如一个高速LAN环境，过多使用epoll,效率相比还有稍微的下降。但是一旦使用idle connections模拟WAN环境,epoll的效率就远在select/poll之上了。3.1 所用到的函数：（1）、int epoll_create(int size)该函数生成一个epoll专用的文件描述符，其中的参数是指定生成描述符的最大范围（2）、int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event)用于控制某个文件描述符上的事件，可以注册事件，修改事件，删除事件。如果调用成功返回0,不成功返回-1int epoll_ctl{int epfd,//由 epoll_create 生成的epoll专用的文件描述符int op, //要进行的操作例如注册事件，可能的取值EPOLL_CTL_ADD 注册、//EPOLL_CTL_MOD 修改、EPOLL_CTL_DEL 删除int fd, //关联的文件描述符struct epoll_event *event//指向epoll_event的指针}（3）、int epoll_wait(intepfd, struct epoll_event * events,int maxevents, inttimeout)用于轮询I/O事件的发生，返回发生事件数int epoll_wait{int epfd,//由epoll_create 生成的epoll专用的文件描述符struct epoll_event * events,//用于回传代处理事件的数组int maxevents,//每次能处理的事件数int timeout//等待I/O事件发生的超时值//为0的时候表示马上返回，为-1的时候表示一直等下去，直到有事件//为任意正整数的时候表示等这么长的时间，如果一直没有事件//一般如果网络主循环是单独的线程的话，可以用-1来等，这样可以保证一些效率//如果是和主逻辑在同一个线程的话，则可以用0来保证主循环的效率}epoll是为处理大批量句柄而作了改进的poll。4. epoll的优点：<1>支持一个进程打开大数目的socket描述符(FD)select 最不能忍受的是一个进程所打开的FD是有一定限制的，由FD_SETSIZE设置，默认值是2048。对于那些需要支持的上万连接数目的IM服务器来说显然太少了。这时候可以：(1) 可以修改这个宏然后重新编译内核，不过资料也同时指出，这样也会带来网络效率的下降(2) 可以选择多进程的解决方案，不过虽然linux上创建进程的代价比较下，但是仍旧是不可忽视的，所以也不是很完美的方案epoll没有这样的限制，它所支持的FD上限是最大可以打开文件的数目，这个数字一般远大于2048，具体数组可以查看cat /proc/sys/fs/file-max查看，这个数目和系统内存关系很大。<2>IO效率不随FD数目增加而线性下降传统的select/poll另一个致命弱点就是当你拥有一个很大的socket集合，不过由于网络延时，任一时间只有部分的socket是"活跃"的，但是select/poll每次调用都会线性扫描全部的集合，导致效率呈现线性下降。epoll不存在这个问题，它只会对“活跃”的socket进行操作。这是因为在内核实现中epoll是根据每个fd上面的callback函数实现的。那么，只有"活跃"的socket才会主动的去调用 callback函数，其他idle状态socket则不会，在这点上，epoll实现了一个"伪"AIO，因为这时候推动力在os内核。在一些 benchmark中，如果所有的socket基本上都是活跃的---比如一个高速LAN环境，epoll并不比select/poll有什么效率，相 反，如果过多使用epoll_ctl,效率相比还有稍微的下降。但是一旦使用idle connections模拟WAN环境,epoll的效率就远在select/poll之上了。<3>使用mmap加速内核与用户空间的消息传递这点实际上涉及到epoll的具体实现了。无论是select,poll还是epoll都需要内核把FD消息通知给用户空间，如何避免不必要的内存拷贝就 很重要，在这点上，epoll是通过内核于用户空间mmap同一块内存实现的。而如果你想我一样从2.5内核就关注epoll的话，一定不会忘记手工 mmap这一步的。<4>内核微调这一点其实不算epoll的优点了，而是整个linux平台的优点。也许你可以怀 疑linux平台，但是你无法回避linux平台赋予你微调内核的能力。比如，内核TCP/IP协议栈使用内存池管理sk_buff结构，那么可以在运行 时期动态调整这个内存pool(skb_head_pool)的大小--- 通过echo XXXX>/proc/sys/net/core/hot_list_length完成。再比如listen函数的第2个参数(TCP完成3次握手 的数据包队列长度)，也可以根据你平台内存大小动态调整。更甚至在一个数据包面数目巨大但同时每个数据包本身大小却很小的特殊系统上尝试最新的NAPI网 卡驱动架构。