问题
They ______ on the program for almost one week before I joined them, but still no good results _______ so far
A:had worked ; come out
B:have worked ; came out
C:had been working ; have come out
D:have been working ; have come out
B:have worked ; came out
C:had been working ; have come out
D:have been working ; have come out
正确答案是：
