A:Hello!May I speak ( )Mr.Black?
B:Hello!( ) is Mr.Black speaking.Who's ( ),please?
A:It's David,your student,Mr.Black.
B:Pardon?
A:David,( ) student.
B:Oh,what's ( ),David?
A:I want to go ( ) your home.I'd ( ) you to help me with my English.Are you ( ) now?
B:( ),I'm not free now.Maybe(或许）I'll ( ) free tomorrow.
A:OK.See you tomorrow.
B:See you.