----The task is challenging and demanding. Who do you think can make it?---- ___________my partner have a try? I think she is the right person to do it.

--- 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.

 — _________ I use your telephone?— Yes, of course.

He is ______ outstanding student from ______ university in America. 

He____know the answer, but I’m not sure.