This is Mr. Green and this is Mr. Brown.（）

A.Oh, I have never seen you. 
B.Yes, I am glad.
C.Hello, John. Nice to meet you.
D.How are you?

A.You may ask for help. 
B.I'll give you a hand. 
C.Please do me a favor. 
D.I'd come to help.

A.next  
B.besides 
C.unless 
D.accept