水平面的投影特性

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 示波器实验触发等实验问题假如用函数信号发生器产生一个峰峰值200mv,中“带-250mv偏置”是什么意思 具体要调节什么使用CH2的下降边沿作为触发条件 怎么调节零电位在屏幕中央 我怎么知道 Do you want a friend whom you could tell everything to?这一句中的to提前会变成什么样的句子,为什么to提前了引导词就只能用whom.和原句区别在哪? The missing boy was last seen ___ near the river.A.playing　 B.to be playing　　C.play　　D.to play为什么选A?see的被动语态不用还原to吗?为什么不用B, 示波器的实验步骤要最简洁的. Do you want a friend to whom you could tell everything这个语序怎么去理解～总感觉别扭, 示波器实验1）频率比为1：1里萨如图形何时为椭圆,何时为圆?2）如果Y轴信号的频率fy比X轴信号的频率fx大很多,示波器上看到什么情形?相反又会看到什么情形?