Jill and Kate will go hiking （徒步旅行） with their class tomorrow. They want to take some fruits with them. Jill likes oranges and Kate likes apples. When they get to the market, they can't find any oranges, and the apples are too green. "What are we going to buy now?" asks Kate. "Hey, what's that big round fruit over there?" asks Jill. "I don't know. Let's ask the sales-girl." "What do you call this?" "Youzi," answers the girl. "Why don't we buy one?" asks Jill. "OK, we're going to have lots of fun hiking and eating a new kind of fruit!" says Kate.