The boss took it for granted that his secretary should keep him well-informed.

A．assumed that it was true without doubt

B．believed that it was true without making sure

C．agreed that it was necessary

D．thought that it was beneficial

泵站每台机组投入运行前，应进行机组启动(阶段)验收。水泵机组的各台机组运行时间为带额定负荷连续运行24h(含无故障停机)或7天内累计运行48h(含全站机组联合运行小时数)，全部机组联合运行时间一般为6h，且机组无故障停机次数不少于______次。

A．7
B．5
C．3
D．2