题目

Ann Jones is one of the most interesting people I have ever met; she is only twenty-five, but she has travelled to over fifty different   31  . Five years ago, she was a typist in Birmingham,    32   she decided to give up her   33   and see the world. Since then, her   34   have changed completely. The first time she went   35   was seven years ago   36   she was just 18. She took a boat to France and then hitch-hiked around   37   for five weeks. She has   38   Europe many times since that first trip, of course, but this holiday was the one which made 设等比数列{an}的首项a1=256，前n项和为Sn，且Sn，Sn+2，Sn+1成等差数列．（Ⅰ）求{an}的公比q；（Ⅱ）用Πn表示{an}的前n项之积，即Πn=a1•a2…an，试比较Π7、Π8、Π9的大小．