The boss showed his________ of Tom's hard work in the company by raising his pay to $ 5,000 a month.

A．distinction

B．promotion

C．appreciation

D．reservation

设A为n阶方阵，B是只对换A中第1列与第2列所得的方阵，若|A|≠|B|，则

A．|A|可能为0．

B．|A|≠0．

C．|A+B|≠0．

D．|A-B|≠0．