机动车在环形路口内行驶，遇有其他车辆强行驶入时，只要有优先权就可以不避让。

— I dropped in at your house at about ten last night, but you weren't in. 

— I ______ regular exercises at the club. [ ]

A. did                        

B. was doing

C. had done                  

D. have been doing