You_______that mistake；you were too care_爱下问搜题

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问题选择题

You_______that mistake；you were too careless．

A．should not make

B．should not have made

C．ought not have made

D．must not have made

答案

B

解答题

{a_n}是公比大于l的等比数列，S_n是{a_n}的前n项和．若S₃=7，且a₁+3，3a₂，a₃+4构成等差数列．

（Ⅰ）求{a_n}的通项公式．

（Ⅱ）令b_n=log₂a_2n，求数列{b_n}的前n项和T_n．

单项选择题

现在0.81%是（）存款利率。

A.整存整取三个月

B.零存整取1年

C.1天通知

D.7天通知