—Listen! Is it Linda singing in the next room?    

—No, it _    be her. She is still in Shanghai. [ ]

A. can't                    

B. couldn't

C. may not                  

D. might not

钙质生石灰的有效氧化钙加氧化镁含量为87%，该生石灰为（）。

A、优等品

B、一等品

C、合格品

D、不合格品