— I phoned you yesterday morning. A girl answered, but I didn’t recognize the voice.

— Oh, it ____ my younger sister. She was in my room at that moment.

A. must have been                     B. should have been   C. could have been     D. may have been

— I phoned you yesterday morning. A girl answered, but I didn’t recognize the voice.

— Oh, it __________ my younger sister. She was in my room at that moment.

A. must have been             B. should have been 

C. could have been            D. may have been

— I phoned you yesterday morning. A girl answered, but I didn’t recognize the voice.

    — Oh, it ____ my younger sister. She was in my room at that moment.

A．must have been                                            B．should have been  

C．could have been                                            D．may have been

— I phoned you yesterday morning. A girl answered, but I didn’t recognize the voice.
— Oh, it __________ my younger sister. She was in my room at that moment

1. A.
   must have been
2. B.
   should have been
3. C.
   could have been
4. D.
   may have been

— I phoned you yesterday morning. A girl answered, but I didn’t recognize the voice.

   — Oh, it __________ my younger sister. She was in my room at that moment.

A．must have been         B．should have been   C．could have been        D．may have been