下列对话属于哪种打招呼类型? N: Hi, Uncle! It’s a small world, isn’t it? U: Yeah, it’s great to see you so soon. What’re you doing here? N: I’m shopping together with my roommate. Don’t you think I’m so lucky to meet you? U: Of course! It’s my treat today. What do you want to have for lunch? N: How about McDonald’s? But, I’ve to pay for the dress first. U: No problem! Here you are.