用所给句子补全对话。

A. Is this your mother? B. He's very clever. C. She's very cute. D. He's my big brother. E. And this is my uncle.

A: Look at my photos.

B:

A: No, she's my aunt.

B: She's very nice.

A:  

B: Oh, your uncle is very cool. Who's this boy?

A:

B:

A: This is my little sister.

B: