Many people have been ill from a strange disease these days,       we’ve never heard of before.

A．one

B．that

C．it

D．this

锅炉机组整套启动试运行前监检，蒸汽吹洗质量标准是被吹洗系统的吹洗系数均应大于1，连续二次靶板冲击斑痕粒度等于小于0.8mm，且斑痕不多于（）点。

A、8

B、10

C、12