Alice kept perfectly still, ______ that the dog might attack her. “It was the most ______ experience of my life,” she told me later.

A．frightening; frightened

B．frightened; frightening

C．frightened; frightened

D．frightening; frightening

根据金属腐蚀机理，可分为化学腐蚀和（）两大类。

A.物理腐蚀

B.电化学腐蚀

C.工艺腐蚀

D.外压力电极