—How did you know the details of that surprising news?

—I happened _________ the event then．

A．to be listening                                  B．to have covered

C．to be covering                                   D．to have listened

—How did you know the details of that surprising news?

—I happened _________ the event then.

A. to be listening     B. to have covered   

C. to be covering     D. to have listened

（2010·辽宁东北育才学校高三第一次模拟）    10、—How did you know the details of that surprising news?

—I happened _________ the event then.

A. to be listening     B. to have covered   

C. to be covering     D. to have listened