已知椭圆的两个焦点，通过f1且垂直F1F2的弦长为1，球椭圆的方程

l have three sisters .they are all___ A woman teacher B woman teachers C women teachersDwomen teachers 原子满足最外层8电子稳定结构,我知道怎么做了,这个不用回答.我只是想知道共价化合物它是相互借用电子形成稳定结构的,那如PCl5为什么有单个原子没有形成稳定结构,不应该都是已经稳定了 I have three sisters.They are all()A.woman teachers B.women teacher C.women teachers 请问,压强,海拨,温度,沸点,它们之间的关系是什么? 压强和密度与温度又关系吗? Beth was sitting in an airport hall,waiting to board a plane 完型 --- I must to now.My plane’s ready to board.---Goodbye._______.(Don’t worry / Have a safe trip/ Don’t mention it) It is hardly surprising that eventually Johnny managed to get on board a plane.在这句话中,另外,get on board...是一个固定词组吗?后面可以直接跟a plane吗? when Jack hears that--is coming soon,he goes to board the plane ... 找出Women’s day is in March 中的错误 March 8th is the Women's Day这句话有语法错吗?三八妇女节还是应该写成March 8th is Women's Day Women's Day is on the eighth of March .women's Day is on March 8.这两个句子的日期一个是用序数一个是用基数,请问用基数表达的第二句在读的时候是要用序数词读吗?怎样读,没有the也要读the吗? 三月八号是妇女节用英语说是March the______is Women's Day.中间的空填什么?最好有解释.为什么 is day women's eight March连词成句 Duplex Board 是不是就是我们国内讲的箱板纸双层纸板 是否就是 箱板纸或牛皮卡纸呢？ 英语翻译 duplex board paper 英语翻译反而提出帮助地球人解决地球上现存的严重问题 交流电电源和直流电源串联在和二极管串联,需要考虑二极管的导通电压吗?怎么分析这类题目?急.还串联一个电阻,二极管导通电压为0.7V,问计算时要考虑导通电压吗? 谈谈你对英雄的认识谈谈你的理解 in recent years加什么时态现在完成时是必须么 近几年是recently years,?还是in recent years? In recent years阅读答案In recent years,computer games have become more and more popular in many cities and towns.A lot of small shops and restaurants along busy streets have changed into computer game houses in order to get more money.These place in recent years还是in the recent years?如果不是那一个,那为什么那一个不行? in recent years 前面用什么时态 一场误会作文600字［对不起啊财富值用完了］ 文言文《以学自损不如无学》和《宣王好射》的译文.. 《宣王好射》文言文中“以示左右”中省略了什么部分? 宣王好射古文中的解释加点字和补充省略的句子成分解释家点的字：宣王好射的好（ ） 以示左右的示（ ） 宣王悦之的悦（ ）补充下面省略的句子成分：（ ）以（ ）示左右 （ ）中关而止 宣王好射解释文言文解释! 宣王好射的寓意是? Lucy and Lily enjoyed themselves on the school trip.(改为同义句)Lucy and Lily ___ ___ ___ ___ on the school trip.