—Why didn't you answer my phone when I phoned you at about 11 p. m. yesterday?

   —I ___________and failed to hear the phone.

A. might have slept                 B. must be sleeping

C. might be sleeping                D. must have been sleeping

—Why didn't you answer my phone when I phoned you at about 11 p. m. yesterday?

   —I ___________and failed to hear the phone.

A. might have slept               B. must be sleeping

C. might be sleeping              D. must have been sleeping

—Why didn't you answer my phone when I phoned you at about 11 p. m. yesterday?

   —I ___________and failed to hear the phone.

   A. might have slept               B. must be sleeping

   C. might be sleeping              D. must have been sleeping

—Why didn't you answer my phone when I phoned you at about 11 p. m. yesterday?

—I ___________and failed to hear the phone.

A. might have slept　　　　　　　 B. must be sleeping

C. might be sleeping　　　　　　 D. must have been sleeping

—Why didn't you answer my phone when I phoned you at about 11 p. m. yesterday?

—I ___________and failed to hear the phone.

1. A.
   might have slept
2. B.
   must be sleeping
3. C.
   might be sleeping
4. D.
   must have been sleeping