---Are you still working in Shanghai?

---No, I’m working in Hangzhou now. I ______ in Shanghai for three years.

A．worked

B．have worked

C．had worked

D．was working

（）不包含在作战要素联合一体化之中。

A、指挥系统

B、军事人才

C、战争手段

D、战场环境理念