卷临天下 全国100所名校最新高考模拟示范卷答案

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21.(1)解:因为f(x)=xc,所以f(x)=(x+1)c1分时.f(x)=(x+1)e<0,f(x)单调递减2分当x>-1时,(x)=(x+1)e>0,f(x)单调递增3分所以(x)m=(-1)=-14分(2)证明:要证f(x)+m>e+lnx,即证xe+m>e+lnx,即证(x-1)e2+m-lnx>0分因为m=,所以(x-1)c+m-nx≥(x-1)c-lnx+所以只需证明(x-1)e-1nx+>0对于x>0恒成立6分令g(x)=(x-1)c-1nx+1,则g(x)=xc-1(x>0)设)=x-(x>0,则(x)=(x+1+>0故g(x)=xe在(0,+∞)上为增函数7分又(3)=3-2=3<0,g'(1)=e-1>0所以存在x∈(=2,1),使得g(x0)=08分由g0,得x2即e=x,即一21nx=x则当x∈(0,x)时,g(x)=xe-1<0,g(x)单调递减当x∈(x0,+∞)时,g(x)=xe-->0,g(x)单调递增故g(x)m=g(x)=(x0-1)e-lnx+1=20=1x1=xb+x+2x10分令p(x)=x2+x2+2x-2(2 0所以叭x)在(2,1)上单调递增,(x)>3)=2>0…11分所以(x)≥8(2=2>0,即(x=1=mx+2>012分综上,当m≥时,f(x)+m>e+lnx

【答案与解析】本文是一篇说明文。如果你关心孩子的书写并且希望他们的书写能有所提高,你可以关注本文给出的一些建议,这些建议可能会对改善孩子的书写有所帮助。36.E根据空前“ Before taking steps towards improving handwriting, it is key to understand the exact causes of your teens们如 boor handwriting..”可知,E项“这样的话,你的孩子就可以朝着正确的方向付出努力”符合G根据本段的小标题“ Choose the correct writing tool.”及空前“ Teens generally have to use pens to write.. Choose pensy checking the grip, width, tip and smoothness."可知,G项“查看一些笔之后选择你觉得最适合书写的几支笔”符合。38.D根据本段的小标题“ Pay attention to their posture(姿势).”及空后“ Check your teens' posture when they arewriting.”可知,D项“正确的书写姿势有助于大大地改善书写”符合,39.C根据空前“ The back should be straight; the feet should be well supported; the desk should be at the waist height,adegree or two higher than the height of their bent elbows(肘部).”及空后“ With the proper posture, your teens arelikely to write beautifully."可知,C项“此外,另一只手需要扶着纸张”符合,40.A根据本段的内容、尤其是“ Therefore, it is important to keep your teens staying enthusiastic..”及“ Your positivesupport will help them practise handwriting with more enthusiasm."可知,A项“让他们保持精神高涨”符合。