Sam: Good morning! Can I help you?

Ann: Good morning! I can't find (找到) my sweater.

Sam: OK. What colour is your sweater?

Ann: It's pink.

Sam: Is this your sweater?

Ann: No, it isn't.

Sam: Is that your sweater?

Ann: No, it isn't. A rabbit is on my sweater.

Sam: Oh! It must be (一定是) this one. 

Ann: Yes, thank you. 

Sam: You are welcome!