题目

He knew only that he____ here with a gun in his hand, ____by men who wanted to kill him. A．lay, surrounding                                        B．was lying; surrounded  C．was laying; surrounded                                     D．laid; surrounded 答案：B9．数列{an}的前n项和记为Sn，a1=2，an+1=Sn+n．（Ⅰ）求{an}的通项公式；（Ⅱ）正项等差数列{bn}的前n项和为Tn，且T3=9，并满足a1+b1，a2+b2，a3+$\frac{1}{2}{b_3}$成等比数列．（ⅰ）求{bn}的通项公式；（ⅱ）试确定$\sum_{i=1}^n{\frac{1}{b_i^2}}$与$\frac{3}{4}$的大小关系，并给出证明．