2022英语周报高一17期答案

【命题视角】本题考查等差数列,考查学生的运算求解能力和逻辑思维能力【解题分析】(1)若选①,由S1=a,即S1=(a1+a12×11==a,得a4=0若选②,由a3+a3=a0+a3,得a3-a3=aio-a2,(a-a3)(a+a5)=(a-a2)(a+a2),2d×2a=8d×2a,从而可得a=0若选③,a=a2a5,得(a1+3d)2=(a1+4)(a1+4d),解得a6=a1+5d=0.(2)()知a=0,设等差数列{()的公差为+=6(=,解得a1+5d=0+(n-1)(3)=9d>0,又a6=0,所以a1+5d=0,若S>0,则Sn(n-1)d>0,即x5a1)>0,解得n<1,所以n的取值范围是(n1n<10,n∈N)

第一节参考范文:Last Friday evening witnessed a breathtaking English Singing Contest in our schoolstadium, where 15 singers competed for"The Best English Singer of the YearThe singers, who had stood out from the first round of selection, gave energeticperformances on stage. Throughout the contest, the atmosphere in the stadium was extremelyexciting, with many students singing along to nearly every song. At last, the award went toZhang Xin from Class 1 Grade 1Everyone agreed that the contest enriched our campus life as well as kindling ourpassion for English learning

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