问题
They____on the program for almost one month before l was arranged to help them. Now, we____on it as no result has come out.
A:had been working: are still working
B:had worked were still working
C:have been working have worked Dhave worked are still working
D:have worked are still working
B:had worked were still working
C:have been working have worked Dhave worked are still working
D:have worked are still working
正确答案是：
