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已知A,B,C是△ABC的三边,试说明A^2-B^2-C^2-2BC的值是正数、零还是负数 1减根号3加2减根号3等于多少? 不等式 log1/2(x平方-1）大于等于零 什么叫海拔?海拔是什么概念? 海拔的概念海拔海平面为基准,哪里的海平面?海水动的是液体,如何测海平面?一定能得到一个很精确数吧,不然,如何能测得珠峰8848.13米,精确到厘米,最近的测量一定更精确.另外,气候变暖导致 海拔和水位是一个 水位就是 水面距海平面的距离吗? 西方艺术史经历了那些关键历史时期?如：文艺复兴时期 根据句子后面括号内的词或短语填词1、Gold is a （） metal（very valuable）2、The villagers had （) the well dry and could get no more water （pushed by machines）是根据意思填词 求极限 写出来 求极限, 求极限,写个过程 这个求极限的过程怎么写. 求极限, “欧洲文艺复兴运动是一场伟大的思想革命”的论文 有一只玻璃瓶,它的质量为0.1KG,当瓶内装满水时,瓶和水的总质量为0.4KG,用此瓶装另外一种液体,瓶和液体的质量为0.64KG,求这种液体的密度 a表示一个有理数,|a| 阅读短文,用括号中所给单词的适当形式填空.Babies’ body language can tell you a lot ofinformation,76 (include) what they want or need.If you can 77 (understand)babies’ body language 78 (good),you can take better care of 79 (they). 综合填空.根据短文意思,选择括号内单词,用适当形式填空（help,animal,do,dog,friend,with,house,some,people,be)短文：Animals are our_______.We can find different kinds of _________on the earth. _________animals are living in big 根据短文内容,用括号内所给单词的适当形式填空they (have) four classes in the morning and two in the arter-noon.Bruno often (fly) kites with his friends.On sundays he often （do） his homework and helps her parents (do) some shopp 写一个1到10 之间的阶乘 导数和极限的区别是什么 极限不就是斜率么 导数值好象也是斜率 但是为什么 常数的极限是它本身 而导数是0呢 阅读短文,根据短文内容和首字母提示完成单词,使短文意思完整、通顺.There is a photograph on my desk.When I see it,it always r_________(1) me of the concert which was held in our city two years ago.Li Yuchun held the concert. （英语）阅读短文,根据首字母补全单词.There are 12 months in a year.In different moths,we have different e____.Our school's birthday is september 1st.It's the ninth month of ten year.So we have School Day in that month.There are Christ 三x减y加z等于四二x加三y减z等于十二x加y加z等于六 求极限!过程详解! 分解因式a3+a+1 求极限：请不要用罗毕达方法，图片解答优先： 分解因式a3+1a的三次方, 求极限,请不要用罗毕达方法请不要用罗毕达方法 Lim[(x^2+1）/x+1)-ax-b=0 当x→∞,求a,b. 极限：请勿使用罗毕达方法： 请给位英语达人帮我把这篇小短文根据括号中的词的适当形式填空,Tom：That's terrible.I had a bad cold yesterday.Lucy：Oh,you had better--56---(drink)cold water.Tom：Yeah,my mother has already told me-----57------（not do