完成对话：在对话后面的句子中选出正确的填入空白处。

Jim: Excuse me, Ann. Whose black dog is this? Is it yours?

Ann: Let me have a look. 1.             . I think it's Sam's. My dog is brown.

Jim: Sam, look at the dog behind the tree. 2.            ?

Sam: Sorry, it isn't mine. My dog is black and white. I think it looks like Mary's.

Jim: 3.            ?

Sam: She's my friend. Look! She's over there. Let's go and ask her.

Jim: 4.            .

Sam: Hi, Mary! Is that dog yours?

Mary: 5.            .

Sam: It's a lovely dog! Don't lose it!

Mary: Yes, thank you.

A. Who's Mary

B. OK, let's go

C. Oh, no it's not mine

D. Oh, yes. It's mine

E. Is it yours