Amy is at home now.

Amy: What are you doing, Mum?

Mum: I'm making soup(汤). Can you help me?

Amy: Of course. 

Mum: Can you go to buy some tomatoes?

Amy: OK. 

Amy is in a shop now.

Salesman: Can I help you?
Amy: I want some tomatoes. How much are they?

Salesman: Eight yuan for four. 

Amy: Four, please. 

Salesman: OK. Here you are.