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someone is knocking at the door.who [ ]it be?A;mustB;canCmayD;shall必须有理由 请问大家谁有《剑桥雅思8》的听力音频,麻烦发我邮箱里!doutianchi@126.com 谢谢! There is someone knocking at the door.为什么用“knocking”,要加“ing”? 剑桥雅思7的听力谁有?帮忙发到yyxxi@126.com 谢谢~ there's someone knocking at the door.等于什么最好用there‘s开头 已知集合A={x丨x2+2（a+1）x+a2-1=0}B={x丨x2+4x=0}A∩B=A求实数a的取值范围 雅思和托福的英文全拼是什么? 求剑桥雅思真题3--6的MP3格式听力,刚买了正版真题,发现CD无法复制.邮箱xifengbei@126.com 急求雅思45678真题听力mp3,拜托也发到我邮箱啊hm20070101@126.com. 求雅思剑桥真题8听力答案 邮箱ymll1120@126.com 麻烦能否发给我谢谢!急! —There is somebady at the door.Who _____ it be?—It ______ be Mr.Huang ,the driver.I asked him to come and get me this time.A.may;must notB.will;may C.can;must notD.could; must 将下面句子改写成only引导的倒装句We can work out this problem only in this way.You will go there only by boat.He came to the meeting only after being asked several times.如何改写啊~遵循什么原则? 文章写好后务必交我校刊编辑部,不得体的词语是哪个? 文章写好后,立即交到社刊编辑部,也可以直接交给我这句话哟什么语病啊.如果是,应该改成什么?、 there is a knock at the door.it is the second time that someone _____ me this evening.A had interrupted B would have interruptedC interrupts D has interrupt用完成时我知道.但我觉得主句不用过去时为何不选D? Look!There is someone _____(敲）at the door. There is someone knocking at the door.It may ________ (be) the postman.如题 用定义证明极限limcosn/n(2n+1)=0 Someone is knocking at the door.____ is it? 证明数列1+1/3+1/5+…+1/(2n+1)-0.5*ln(n+1)有极限 设四边形ABCD相对的顶点A、C和B、D与不在四边形的边或它们的延长线上的一点P连接而成的四条直线,与对角线BD和AC或它们延长线依次交于点E、G和F、H,求证：(AF/FC)*(BG/GD)*(CH/HA)*(DE/EB)=1 平行四边形ABCD内有一个点P,连接PD、PC、PA、PB,三角形ADP的面积为2,三角形DPC的面积为5,求三角形PDB的面积. 解决一下这道几何题 请帮我解决几道几何题1.在三角形ABC中,角A=90度,分别以AB,AC为边向外作正方形ABDE,ACFG,设CD交AB于K,BF交AC于L,求证AK=AL2.在三角形ABC中,角BAC=90度,AD是高,DE垂直AB于E,DF垂直AC于F,求证:AD三次方=BC*BE*CF 已知：如图,P是正方形ABCD内点,∠PAD＝∠PDA＝150．求证：△PBC是正三角形． 求好心人发剑桥雅思6、7 PDF+MP3……谢谢谢谢!18662961614@126.com 有剑桥雅思4-7的听力原文吗?哪位好心人能发给我吗 a8696466@126.com 非常感谢 急需剑桥雅思4－7真题解析,哪位好心人可以发给我,不胜感激~!haihaoyouni@126.com 第一个数是1第二个数6第三个数是15第四个数是28第五个数是45第n个数是? Do not make any noise .There is someone knocking at the door .（改成同义句）（）（）.There is （）（） on the door. Listen,l hear someone knocking at the door的同义句 Listen!There is ()() at the door 在五位数字互不相同的五位数中,能被36整除的最大数是多少?