－My parents         our home for a few hours when I arrived. I didn’t meet them.

－You could call them if you wanted to know where they were.

A．have been away from

B．had been away from

C．had left

D．had gone

安全阀试压时开启和回座试验次数不少于（）次，试验过程中，使用单位及有关部门应在现场监督确认。