题目

   The village of Hengly was going to have the Bean Olympics.It was a competition to see which kind of bean would grow the fastest and tallest.Everybody was excited.They couldn’t waited to show their best plants.    Cassie knew clearly which bean she would choose for the competition,for her family had planted a special “family bean.”It was a flat bean that her greatgrandparents had brought from Sicily.Her grandmother planted the beans every year and served them at many meals.Cassie was sure they would be unbeatable beans.    However,the plan did not work out that way.Altho 规定运算＝ad－bc，若＝1－2i，设i为虚数单位，则复数z＝________.