题目

据统计，2017年国庆黄金周内旅游市场接待游客约589000000人次.589000000这个数用科学记数法表示为（ ） A . 589×106 B . 58.9×107 C . 5.89×108 D . 0.589×109 答案：CShortly after the accident, two ________police were sent to the spot to keep order. [　　] A．dozen ofB．dozens C．dozenD．dozens of