He was watching her doing it with a ________ look on her face, as if to say that she would not change her mind.[ ]

A．determining  

B．determined

C．sceptical  

D．secure

超临界直流锅炉启动时要求保证从启动到MCR全过程的安全性，防止亚临界参数下的（）和超临界参数下的（）以及沿宽度方向上的（）。