问题
选择题
等差数列{an}和{bn}的前n项和分别为Sn和Tn，且
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答案
∵等差数列{an}和{bn}的前n项和分别为Sn和Tn，
=Sn Tn
，2n 3n+1
=a5 b5
=9a5 9b5
=s9 T9
=18 28 9 14
故选D．
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等差数列{an}和{bn}的前n项和分别为Sn和Tn，且
|
∵等差数列{an}和{bn}的前n项和分别为Sn和Tn，
=Sn Tn
，2n 3n+1
=a5 b5
=9a5 9b5
=s9 T9
=18 28 9 14
故选D．
Coke(可乐)is one of __ drinks in the world. A lot of people enjoy __ it. But now people begin to believe that it’s not a good drink for health. There is lots of _ __ __ in the coke. Having much sugar is __ _ for people. And it also has some caffeine(咖啡因)in it. The caffeine can get people into the habit(习惯)of drinking more coke when they feel __ . If they don’t drink coke they __ bad. And __ __ thing is some people can’t work or study __ drinking several cups of coke every day. More and more people want to cut down the coke they drink and ask _ __ help from the doctors. If you like drinking coke very much, I think you must have the Coke Habit. In fact drinking more fruit and vegetable juice is __ __ for you.
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