Is it he or you ________ in charge of the job and supposed to complete it on time?.

A．who is

B．that is

C．who are

D．whom are

下列关于水的叙述，正确的是（　　）

A．在水中加入明矾可以杀菌消毒

B．石灰岩地区的井水适合直接饮用

C．净化水的方法有吸附、沉淀、过滤和蒸馏等

D．生活污水直接排放不会造成水污染