扑救粮食仓库火灾，一般应使用()水流，防止粉尘爆炸和水渍损失

A、开花、直流

B、直流、喷雾

C、直流、喷雾

D、开花、喷雾

I often have the case ______ I can't recognize my friends' voice on the phone.[ ]

A. which  

B. that  

C. of which  

D. where