钢铁联合企业能耗指标达到：吨钢综合能耗高炉流程低于( )标煤，电炉流程低于( )t标煤。

A．0.7 0.7
B．0.4 0.7
C．0.7 0.4
D．0.4 0.4

After using a C0₂ portable extinguisher,it should be（）.

A.put back in service if some CO₂ remains

B.hydrostatically tested

C.retagged

D.recharged