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1.At what number will the general manager ____________ that call?A.turn back B.return C.phone back D.give back 2.For further information,please ____________ 54362163,extension 205.A.get in touch B.communicate C.contact with D.contact 3.In spring peop 1）Can you help me _____ my English?A.with B.of C.learning D.about2）Bob can play ____ tennis but he can't play _____ violin.A.the,the B./,/ C.the,/ D./,the3）Do you often go to ____ football games _____your friends?A.see,and B.look at,with C.watc 已知F1,F2为椭圆的焦点,P为椭圆上任意一点,∠F1PF2=45°1 求椭圆离心率的 取值范围2 求证：三角行 F1PF2 的面积 只与 椭圆的短轴长 有关为什么我的（1）算出了一个很夸张的数字,还有一个无解 已知F1,F2为椭圆x^2/100+y^2/b^2=1（0＜b＜10）的左右焦点,P是椭圆上一点.若∠F1PF2=60°且△F1PF2的面积为64√3/3,求b的值? 氯气有毒,为什么还可以用来消毒? The doctor knew how to____an emergency like this.\x05A.deal in B.settle with C.act on D.cope with2.It is wrong to___a person of a crime unless you have proof that he is guilty.blame B.accuse C.charge D.warn 3.The repairman examined car engine ____but 求答几道英语选择题 设F1,F2是椭圆的两个焦点,若椭圆上存在点P,使角F1PF2等于120度,则椭圆的离心率e的取值范围是多少? 已知F1,F2是椭圆的两个焦点,P为椭圆上一点,若角F1PF2=90度,求椭圆离心率的取值范围我自己算了一下 是用的余弦定理来表示写的可是是错的 能不能用余弦的那种方法写一写 非常感谢@@@@@!它到 求答 这道英语选择题怎么答?In my opinion,all our teacher()good to us students at present.He is very strict with us.A.does does does B.does do doC.does does do D.did do does并请解释一下原因 1.Both Japanese and French are now to me.I don’t know ______ of them.A both B all C either D any2.There are many trees ______ of the road!And ______of the trees is growing larger and larger.A on both side;a number B on each sides; a number C on bot 已知椭圆的两个焦点坐标分别是F1(-4,0),F2(4,0),椭圆的弦AB过点F1,且三角形ABF2的周长为20.求椭圆的标准方 已知F1、F2是椭圆x^2/a^2+y^2/b^2=1(a>b>0)的两个焦点,AB为过F1的弦,则三角形ABF2的周长是 2道化学问题（并说明理由）1.生活中常见的下列现象,发生化学变化的是A.冰雪融化 B.生米煮成熟饭 C.湿衣服晾干 D.玻璃杯炸裂2.常温常压下,不适宜用物理性质区别的物质组是A.酒精和食醋 B. 1,等体积、物质的靓浓度的硫酸,氢氧化钠溶液分别放在甲乙两烧杯中,各加入等质量的铝,生成氢气的体积比为5：6,则甲乙两烧杯的反应情况可能分别是（B）A甲乙中都是铝过量B甲中铝过量,乙 I will leave here as soon as I —— my bookA,will get B,got C,get D,am getting you can drink ice water ( ),but not right after sports.A.early B.earlier C.late D.later there are (8) kinds of drink for (9) to choose8:A.a lot B.a lot of C.much D.a little9:A.yourself B.you C.your D.yours 过椭圆4x^2+2y^2=1的一个焦点F1的弦AB与另一个焦点F2围成的三角形ABF2的周长为 90.It's half past eleven____my watch.1on 2by 3at91.Is she____?Yes,she can___,too.1swim/run 2swimming/running 3swimming/run92.Alice's birthday is on____.1Ist June 2June one 3June Ist93.This is not_____book.____is new.1my,My 2mine,My 3my,Mine94.___cloc 12、将固体NH4I置于密闭容器中,在一定温度下发生下列反应：① NH4I(s) NH3(g)+HI(g),2HI(g) H2(g)+I2(g).达到平衡时,c(H2)=0.5 mol•L-1,c(HI)=4 mol•L-1,则此温度下反应①的平衡常数为A.9 B.16 C.20 D.25最 求教英语选择题再次再次的求教42.Don't look out of the window._____me,please.1looking 2looks 3look at 4see43.The book is____.It's not_____.1my /your 2mine/your 3yours/mine 4your/mine45.Hurry,we are______.1lately 2late 3early46.My watch___ 现有由盐酸、硫酸组成的混合酸.为了测定混合酸中硫酸和盐酸的溶质质量分数.设计了如下实验方案：（实验一)取三份混合酸液各100g,分别缓慢加入50g、100g、150g某BaCl2溶液中,测得的实验数据 已知椭圆x^2/25+y^2/16=1的左右焦点分别为F1,F2,弦AB过F1,若△ABF2的内切圆周长为π,A,B两点的坐标分别(X1,Y1),(X2,Y2),则|Y1-Y2|值为? 某地下水是硬水,含有Ca2+,和大量Mg2+,用Ca{OH}2,和Na2CO3,使硬水软化,先加哪一个 一道并不难的化学题,仅用一种试剂鉴别物质：苯、CCl4、NaI溶液、NaCl溶液、Na2SO3溶液.下列试剂中不能选用的是（ ）A.溴水 B.FeCl3溶液 C.酸性KMnO4溶液 D.AgNO3溶液 求教英语选择题1.( )Sandy is a boy ________ class Two. A.in B.for C.of 2.( ) _________ on the desk? There's a pencil A.Where's B.What's C.Whose 3.( )John likes _______. 现有MgCO3和NaHCO3的混合物,甲 乙两位同学分别称取一定质量的该混合物来测定其中两种成分的质量比 请回答下列问题 甲同学称取2.52g混合物并向其中加入足量2mol/L的盐酸生成标准状况下气体 设F1,F2分别为椭圆C:x^2/a^2-y^2/b^2=1(a>b>0)的左,右两个焦点(1)若椭圆C上的点(1,1.5)到F1,F2两点的距离之和为4,写出椭圆C的方程和焦点坐标(2)设点Y是(1)中所得椭圆上的动点,求线段F1Y的中点的轨迹方 已知椭圆x^2/a^2+y^2/b^2=1（a＞b＞0）的两个焦点分别为F1（-c,0）,F2（c,0）（c＞0）,过点E（a^2/c,0）的直线与椭圆交于点A、B两点,且F1A//F2B,|F1A|=2|F2B|.1.求椭圆的离心率.2.求直线AB的斜率.3.设点C与点 设F1 F2分别为椭圆C：x^2/a^2+y^2/b^2=1 (a>b>0)的左右两个焦点（1） 若椭圆C上的点A（1,3/2）到F1 F2两点距离之和为4 写出C的方程和焦点坐标（2） 已知椭圆具有性质：若M N是椭圆C上关于原点对称的 i can play computer games______an hour every day.A.for B.to C.inthe hamburgers taste very_____.A.nice B.nicely C.well