2022英语周报高一XJCM答案

19.(1)当n=1时,S1=2a1-2,得2;……………………………………2分当n≥2时,S。=2an-2①,S1=2a-12②①-②得,=2;……………4分所以数列{an}是以a1=2为首项,以2为公比的等比数列,即an=2°;………………5分(2)由题,得bn=n=n·(1),因为Tn=b1 b2 b … bn2 bn1 b,所以T=12 2×()2 3×()3 … (n-2)(-)=2 (n-1)() n()”①,T=()2 2×()3 3×() …2)(-)m1 (n1)(÷)” n()1②,①-②,得T2 ()2 ()3 (-)1 ()n(2所以,T。=2-(n 2)x(-)”,……………………………10分显然,T。<2,因为T,1-Tn=>0,所以数列{T,}是递增数列,且T1=2-32因此≤T。<2.…………………12分

OFiona's mother listened carefully to her story. Then she said, "If you really want true friends, you will haveto give them real time and affection. For a true friend you must always be available, in good times and bad. Youcant be a close friend to everybody. There just isnt enough time to be available for everyone, so it's only possble to have a few true friends. The others will be common friends or people you know, but they won t be closeHearing this, Fiona decided to change her ways so that she could finally have some true friends. Thatnight, in bed, she thought about what she should do. She thought about her mother. Her mother was alwayswilling to help her; she put up with all of Fiona's dislikes and problems she always forgave her; she loved hea great deal.. That was what makes friends

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