问题
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
B:had worked were still working
C:have been working have worked
D:have worked are still working
正确答案是：
