--- Listen! David is talking happily with his mother in the next room. --- It ______ be his mother. She has gone to Yunnan to be a volunteer doctor.
The doctor will return from Macao ______ a few days.
There is no doubt _______ your answer is right.
These photos_____ me_____ the old days when I was young.
His friends found ______ necessary to tell him everything about his father .
---Can you hear a girl ____ next door, Miss Zhou? ---Yes. How beautifully!