—Can you come to have dinner with me this evening?  

—I'm afraid not. I _______ take care of my grandmother. She is ill.   [ ]

A. can't        

B. have to      

C. may      

D. could

满意度的高低不影响客户的稳定性，满意度低的客户也可能成为商业银行的忠诚客户。