已知坡度求斜长

Help!数列题1,某城市1996年底人口为20万,住房面积大约为8平方米,计划到2000年底人均住房面积达到10平方米,如果该市人口平均增长率控制在1%,那么要实现上述计划,每年该是要平均新建住房面积 take up take是什么意思 想了解中国经济地理,最好是有地理图册,该读什么书? 语c群里弧回来和垫是什么意思求大神求大神. 数列{an],n属于N,满足a0=0,a1=2且对任意n属于N有啊a(n+2)=2a(n+1)-an+2,求数列{an}的通项公式2,Tn=1/3a1+1/4a2+……+1/(n+2)an,求Tn 已知数列{an}中,a0=a1=1,且根号ana（n-2）-根号a（n-1）a（n-2）=2a（n-1）求数列{an}的通项公式．画括号的n-1 n-2均为角标 数列{an}中,a0=0,a1=1,2a（n+1）=2an+a（n-1),求an的通项公式. Tate sounds interesting.I don't have a soccer ball.合并为一句 Do you want a friend whom you could tell everything to ,like your deepest feelings and thoughts...Do you want a friend whom you could tell everything to ,like your deepest feelings and thoughts?的翻议是什么? (seen)to entered the room ,he was asked to the policeman.为什么不是having been seen? 高中英语Mr. Write was seen ( )the palace museum. A.enter B.to enter C.entered Dto have entered,B or D? 有什么规律 制定全抗战路线的会议是A.八七会议B.遵义会议C.洛川会议D.瓦窑堡会议 Tim was crossing the street when a soeeding car drove ____________ close to him.A.dangerous B.danger C.dangerouslyhelp me 有什么 规律 确定实行全面抗战路线的会议是什么会议 He was seen to cross the street.请划分一下句子成分 有什么规律呀 look around when____the street.a.crossing b.crossed c.to cross d.across 请详细说明理由. ______who leave the room last ought to turn off the lights.A.Anyone B.Who C.Those D.Whoever 过马路之前要注意左右看翻译成英语是什么题目如下：Be__to look __ __ before you__the road. 记得过马路前要注意看信号灯（traffic lights） before you cross the road 过马路前先看看两边Look at () () before you cross road. do you want a friend to whom you could tell everything是什么从句 Do you want a friend whom you ____ tell everything to A can B could 选哪个为什么? The room had a wall through which the scientists could observe what happened without being seenThe room had a wall 后面是否应该加逗号呢? The thief entered the room without ( )A.noticing B.being noticed C.having noticed D.having been noticed where he could see without being _____ being seen by others,he slipped out of the meeting roomA.To be avoidedB.AvoidingC.To avoidD.Avoided选哪个?为什么? 快速地过马路的英文是什么?不是quickly cross the road 吗(⊙_⊙)? 1123581321什么寓意