It was several minutes before I was ____ of what was happening.

A．fond of

B．realized

C．aware of

D．prepared of

计算题：测得某自来水的碱度JD＝5.70mmol∕L，硬度YD＝7.55mmol∕L。试求自来水中的碳酸盐硬度、非碳酸盐硬度和负硬度的数值。