They ______ on the program for almost one week before I joined them, and now we 

题型：月考题难度：来源：

They ______ on the program for almost one week before I joined them, and now we  _______ on it as no good results have come out so far.
A. had been working; are still working  
B. had worked; were still working
C. have been working; have worked    
D. have worked; are still working

答案