While I was in the university, I learned taking a photo,（）is very useful now for me.

A.Good idea
B.Yes, it's nice
C.Yes, please
D.I can't decide

A.Who are you?
B.This way, please
C.I don't want to say anything
D.What can I do for you?

A.He's gone to
B.He's been to
C.He isn't in
D.He's out