— Did you catch what I said?

— Sorry. I ______ a text message just now. [ ]

A. had answering    

B. have answered    

C. would answer    

D. was answering

对数字数据的线性化处理是指（ ）

A．对X线的线束硬化效应进行校正

B．对空气值进行减除

C．对零点漂移值进行修正

D．对扫描数据的总和进行检验和校正

E．对处理好的数字数据再进行褶积处理