铝盐和铁盐的净水原理

在等差数列an中,a3+a7-a10=6,a1-a4=-6,则s13等于?A:168 B:208 C:78 D:152有具体步骤不 已知{an}为等差数列,有且a2+a3+a10+a11=48,求a6+a7 -What made you so upset?-_____my house _____saying goodbye.A.Jim left,without B.That Jim left.wit..为什么啊 is it the email that you received yesterday ______makes you upset?A.which B.what C.that D.when说是强调句.说是去掉it is that,句子说得通就是强调句.可是我就想问了.it is the email which makes you upset.也可以说是定语从 鸭妈妈检验丑小鸭是不是自己孩子的方法是 丑小鸭 鹅妈妈把蛋怎么把蛋丢在鸭妈妈窝里 That's exactly ( )I feel right now.填what还是how? that's exactly what i had in 中心对称图形1、已知四边形ABCD是中心对称图形,AB=1,BC=2,那么CD=2、已知BC为等腰三角形纸片ABCD的底边,AD垂直于BC,角BAC不等于90度,将此三角形纸片沿AD剪开,得到两个三角形,若把这两个三角形拼 初三数学“中心对称图形（二）”如图一O为圆柱形木块底面的圆心,过底面的一条弦AD,沿母线AB剖开,得剖面矩形ABCD,AD=24cm,AB=25cm,若弧AmD的长为底面周长的3分之2,如图二所示.（1）求⊙O的半径 feel left out是什么意思 i feel left out 是什么语法结构 He began to feel left out.为什么feel后可以接动词? feel let out什么意思 feel really left out “left out” 是指被冷落、离开、剩下还是多余 ___Do you know what the population of India is ?___Not exactly.I only know that China has a _____population than India A.large B.larger C.much D.more 顺便问一下什么是中心对称图形 初三关于中心对称图形的几道题如图,已知平行四边形ABCD与等边三角形ADE,求作一点F,使图形ABFCDE为中心对称图形.写出作法写理由 丑小鸭是被遗弃在鸭场的天鹅蛋么 丑小鸭是天鹅蛋,他是被鸭妈妈孵的丑了,还是天鹅小时候就丑呢? Left is not left ____has made China ___she is today?A.what;what B.that;what C.what;what D.that;that 甲数的3分之1与乙数的8分之1,甲数是乙数的百分之几? We have many clubs.Jim joins our soon.这句话如何翻译? 第六题,需要画图,写公式 We will always be here 怎么读 求英语翻译奇才把李清照的(一剪梅)用英语翻译(所有的) 李清照的《一剪梅》怎么翻译? I am always here to understand I am always here .有错吗?I am always here to support and encourage you along the way.这句话对吗?有I am always here的说法吗 I'm as good as new.这样翻译成汉语? It is the day to make up class today. Make up翻译中文