据20世纪80年代材料，占世界人口1/4的发达国家拥有世界报纸发行量的（）
A．1/2
B．1/3
C．3/5
D．3/4
参考答案：D
先来先服务、短作业优先、最高响应比优先、优先数法调度算法中最短的作业平均周转时间是 【6】 。
It was not until she had finished all her work_______home tired
A．did she return
B．that she returned
C．when she returned
D．that did she return
