The telephone _____ three times in the last hour, and each time it _____ for my sister.

A. had rung; was    B. has rung; was     C. rang; has been           D. has been ringing; is

The telephone _____ three times in the last hour, and each time it _____ for my sister．

A．had rung; was                                     B．has rung; was

C．rang; has been                                     D．has been ringing; is