2022-2022英语周报高考外研第14期答案

(19)满分15分(1)解:设等差数列{a等比数列{bn}的公比为q·由a=1,a3=5(a4-a),可得d=an}的项公式为an=n,由b=1,b=4(b-b)又q0,可得可4付肉=2,从而(内}的通项公式为=2(Ⅱ)证朔<()可得Sn(n+1)2故S,Sn2=n(n+1)(n+2)(n+3),2),从而SSn12-S21=-(n+1)(+2)<0,所以SSn2

第四部分写作第一节Dear Jack,Welcome to our school to study as an exchange studentAs for how to borrow books from the school libraryyou need to have your student ID card and present it to thelibrarian, who can register for you. Then you can go to thebookshelves to look for what you need. You can borrow 2books once and keep them for a week in order that you canhave enough time to finish reading them. If you haventread the book through, you can renew it. You' ll have topay for it if you get the book damaged or lost.hope all this can be of help to you. For morenformation, don,t hesitate to ask meLi Hua

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