某批零件有4件,共经历4道工序,其工序顺序及单件工序时间分别为t1=10min,t2=5min,t3=12min,t4=7min.平顺移动方式下的时间是:( )。
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