Assistant: Can I help you?

Mom: Yes, please. A pair of trousers for my son.

Assistant: What size?

Mom: Medium.

Assistant: How about this pair?

Mom: Are they nice, John?

John: I don't like green, mom.

Mom: What color do you like?

John: I like blue trousers.

Assistant: Here is a pair of blue trousers.

Mom: Do you like this, John?

John: Yes, I do.

Mom: How much are they?

Assistant: 35 yuan.

Mom: OK, we'll take them.