题目

Tom shook his piggy bank again. There was nothing left! He carefully ________ the coins that lay on the bed. All he had was $24.52(about 153 yuan). The ________ he wanted was at least $90! How was he going to get the rest of the money? His friends all had bicycles. It was_______to hang out ( 闲逛 ) to with people when you were the only one without a bicycle. He thought about _______ he could do. There was no point asking his parents, for he knew they had no extra money.The only way he could get more money was to earn it. He would have to find a _______.He decided to ask Mr. Clay for advice.在等差数列{an}中，a1=92，其前n项和为Sn，等比数列{bn}的各项均为正数，b1=1，比为q，且S2+b3=21，S2-b3=q（Ⅰ）求通项公式an与bn；（Ⅱ）设数列{cn}满足cn•Sn=1，求{cn}的前n项和Tn．