PDH管理能力问题弱,给建立()带来困难。
A.服务端口
B.检测系统
C.告警系统
D.集中式管理网
参考答案:D
The plane ______ when we got to the airport. [ ]
A. had taken off
B. was taken off
C. will take off
D. is taking off
一个任务单可以关联多个工作票吗?