按时间范围,以所检索课研究的发生时间为检索起点,按事件发生、发展时序,由远及近,由旧到新的顺序查找。这种检索方法叫做( )
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
免费的网站请分享给朋友吧