--- My new iphone was stolen when I took a bus yesterday.

---- ____________.

A．I’m sorry to hear that

B．it doesn’t matter.

C．Don’t be silly

D．I’d love to

为了节省氮气，对开工系统进行首次充氮气置换的方法是（）

A、随充入随放空

B、充入后部分放空

C、充入并循环后部分放空

D、充入并循环后全部放空