■回报率的非期望部分由下一个月内显示地信息导致, 例如 News about flyers'research Government figures released on the gross national product(Gnp) Results of the latest arms-control talks Discovery that a rival' s product has been tampered with News that Fleyers' sales figures are higher than expected a sudden drop in interest rates The unexpected retirement of Flyers founder and president◼ 回报率的非期望部分由下一个月内显示地信息导致， 例如 ◼ News about Flyers’research ◼ Government figures released on the gross national product (GNP) ◼ Results of the latest arms-control talks ◼ Discovery that a rival’s product has been tampered with ◼ News that Fleyers’sales figures are higher than expected ◼ A sudden drop in interest rates ◼ The unexpected retirement of Flyers’founder and president