A【解析】本题考查等差数列的通项公式,前n项和,等比数列的概念和数列的基本运算.设数列的公差为d≠因为成等比数列,所以2 aa4=,即1(a1+3d)=(a1+2d)2,a=-4d;则S3-S2_3_a1+2d_-4d+2d =2. Ss-S3 a4+as 2a+7d -8d+7d故选A 解题步骤 等比数列是指一个数列中每一项与它前一项的比...
根据汉语意思,选择恰当的选项。1.an__y(生气的) A.ur B.gr C.er 2.m_ss(想念) A.i B.a C.e 3.tir__(疲倦的) _ 快乐寒假18_2025年新课堂假期生活寒假用书北京教育出版社五年级英语全一册外研版
[题目]根据汉语意思.选择正确的字母或字母组合补全单词.1.th ty A.ir B.ar C.is A.an B.in C.on3.cl ner A.ee B.ea C.ae A.a B.u C.e A.o B.a C.e
在下列名词前填上a或an。 1. ___ egg3. ___ school5. ___ book7. ___ apple9. ___ Ss11. ___ umbrella 2. ___ cat4. ___ orange6. ___ hour8. ___ car10. ___ Uu12. ___ pupil 扫码下载作业帮搜索答疑一搜即得 答案解析 查看更多优质解析 解答一 举报 1. an 2. a 3. a ...
Crystallographic and sulfur-34-labeling evidence for an oxygen-transfer mechanism and observation of facile exchange of Cr2S5 core sulfurs with 34S. Structures of Cp*2Cr2(.mu.-S)(.mu.-.eta.2-S2)(.mu.-.eta.1-SS.cntdot.SO2).cntdot.SO2 and Cp*2Cr2(.mu.-S)(.mu.-.eta.2-S2)(....
3.{an}为等差数列,Sn为前n项和,SS,S。=S,S,Sg,则下列说法错误的是().A.d0B.a,=0C.SSsD.S和S,均为S的最大值3.{a,}为等差数列,S,为前n项和,S,S,,则下列说法错误的是()。A.ds D.S。和S,均为S,的最大值 相关知识点: 试题来源: 解析 95-|||-解析:由题意得,S-S3=a60,S2...
A. an B. un C. in【2】cl__ss ( ) D. a E. o F. e【3】n__ __se ( ) G. ir . or . ur【4】dinn__ __ ( ) . er . or . ur【5】f__ __st ( ) . er . ir . or 相关知识点: 试题来源: 解析 【1】B 【2】A 【3】C 【4】A 【5】B 【1】lun...
英语智力测试题!1.What letter is an insect?It's___.A.Ww B.Ff C.Bb D.Ss2.What letter should appear next?___.3.What letter is the one you want to know the reason of something?___.4.What stars with T,ends with T and full of ___.5.W
题目 As I walked to the market,I saw an old and dirty man sitting in front of a shop.It was(1) A that he was a beggar looking for help.I made a (2) B that on my way back I would give him whatever (3) AI had.A few feet away was a drunk-looking ...
Subpectoral Biceps Tenodesis in the Management of Tears of the Long Head of the Biceps: Long Term Follow-up (SS-12) Purpose: The purpose of this study was to evaluate and compare the biomechanical properties of a unicortical button with an interference screw used for sub... SC Weber,J ...