阅读对话，判断对错 。

Assistant: Can I help you?

Mum: Yes, please.  I want to buy a pair of sneakers(网球鞋) for my son.

Assistant: What size?

Mum: Size twenty-one.

Assistant: How about this pair?

Mum: I like those blue sneakers.

Assistant: Here you are.

Mum: Thank you.  Are they nice, John?

John: Yes, Mum.  I like them.

Mum: How much are they?

Assistant: They're thirty-five yuan.

Mum: OK.  We'll take them.