— How was your day off during the Qingming Festival?

— Pretty good! We         Xu Xiaoxuan’s former home.

A．visit

B．visited

C．was visiting

D．will visit

CO₂气体保护焊时对焊接区域采用的保护方法是（）。

A.渣保护

B.气保护

C.渣气联合保护