先经元经指的是什么

已知x的平方减去y的平方等于8,x加y等于4,求X ,Y的值 氯、氧、氢组成什么化合物 问一个成语题目将（）（）将,括号里面应该填什么啊? 鸟儿在哪儿住呀? 用绳子栓住小鸟的腿,小鸟会死吗?我养了一只小鸟,我不想把她天天关在笼子里,但又舍不得放飞她,我想用绳子拴住她的腿,然后放很长的绳子让她飞一定距离,然后想让她回来,就沿着绳子拉她 没被关住的鸟叫什么鸟 第九题第一个.两个括号填什么成语? 【清平乐】 春云绿处.又见归鸿去.侧帽风前花满路.冶叶倡条情绪.红楼桂酒新开.曾携翠袖同来.醉弄影娥池水,短箫吹落残梅.请问,这是晏殊的词么?想表达什么呢? 请解释一首词.请解释这首词.道成归阮郎归改道成归.修行人喜知.松峰影里乐希夷.何须唱艳词.姹婴动,虎龙随.云耕坎与离.三千功满赴瑶池.神光相貌奇 给我解释一首词三生何其有幸,万人之中得你垂青.我怀报李之心,奈何你转眼成霜词的背景是：和男朋友冷战 他写的词 估计是伤心了 请特别解释一下最后一句 下面以诗句作谜面,请各猜一成语1危楼高百尺( ) 2谁知盘中餐,粒粒皆辛苦( ) 3夜来风雨声,花落知多少( )4欲穷千里目,更上一层楼( )5明月何时照我还( )6桃花潭水深千尺,不及汪伦送我情( ）7孤帆 快下雨的时候,哪些小鸟会做出什么动作.至少三种鸟. 下雨的时候小鸟都去哪儿了? 为什么小鸟要到下雨的时候不会叫呢? 如图,A,C是函数y=-2/x的图像上关于原点O对称的任意两点,过C想x轴引垂线,垂足分别为B,则三角形ABC面积为 M={θ丨sinθ≥1/2,0 解指数方程 怎么解4^(2x)-2^(2x+2)+3＜0的解集 过氧乙酸见光或受热分解时.能生成一种常见的气体单质和醋酸,该反应符号表达式 两种单质点燃生成化合物的表达式两种不同元素的原子.这两种元素分别组成的单质 英语翻译Most parents love the Internet and want their kids to use it.But a new survey in America finds almost as many also fear the online world — especially social networking sites such as MySpace — and worry their kids will get in trouble w 英语翻译Shakespeare said,\'journeys end in lovers meeting\'.What an extraordinary thought!Personally,I have not experienced anything remotely close to that,but I\'m more than willing to believe Shakespeare had.It was Shakespeare who also said,\'l 英语翻译Do you like twilight?:)I think that they are very good movies but i love scary movies!:)and if you were able to fly to australia in time it would be fun!:PMaybe one day I will afford to be able to travel to different counties including yo 英语翻译乐队:Interpol 歌名:Obstacle 1I wish I could eat the salt off of your lost faded lipsWe can cap the old times make playing only logical harmWe can cap the old lines make playing that nothing else will changeBut she can read,she can rea 请求翻译一下 怎样证明化合物中含有碳和氢元素 请问,组成化合物最多的元素是碳还是氢? 碳(C),钾（K）,氢（H）,有什么化合物?有没有就这个顺序的？（CKH） 碳和氢生成比例为1:1的化合物种类 英语翻译I mean,it's not someone will get used to it,it's kind of dependence..And this is too bad..And of course I do really not want to be part of that kind of people.I don't wanna say it in Chinese because I'm not really comfortable with it.Mayb 英语翻译 英语翻译The FiascoIn the beginning,he wanted to ride the political wave.Given his cowardice,he pulled out and switched to cultural exchanges,as expected.Then,as if the cultures were not grandiose enough,the gay rights kicked in.Somewhere in betwe 用波浪线画出每组中搭配不当的短语,并在横线上加以改正.1.极端自豪 分辨不清 处理事件 约定俗成2.对付进攻 理由充分 封锁消息 热情欢呼3.研制潜艇 特征显著 眺望地面 吐字清晰