题目

阅读理解The city of Venice，in Italy，is one ofa kind. It is built on more than 120 islands，just offarrival. After explaining where my new house was, I told him that I had leftthe key under the doormat. Since I knew it would be quite late before I couldget back, I suggested that be make himself at home and help himself to anythingthat was kept in the refrigerator (冰箱). Two hours later my friend phoned me from the house. At themoment, he said，he was listening to some of my records after having had a nice meal.He had found the pan and meat in the refrigerator. Now, he was drinking 已知a,b分别是6-的整数部分和小数部分,求(2a-b)2的值;