小明和小红对市场上销售的一种分袋包装的豆奶粉发生了兴趣，因为豆奶粉装在充满气体的小塑料袋内，袋内的气体充得鼓鼓的，看上去好象一个小“枕头”，他们认为这种充气包装技术，主要是为了使食品长时间地保鲜、保质，那么这是什么气体呢？
小红猜想是氮气，小明猜想是二氧化碳
（1）请你设计一个简单的实验探究，判断小明的猜想是否正确

（2）你认为食品充气包装，对所充气体的要求是：
①____ ；
②____ ；
③____ 。

   It's Saturday afternoon now . Sally and Sam are talking about what they are going to do tomorrow.
Sally: What are you going to do tomorrow?
Sam : Oh, I'm going to watch a football match .It's my favourite team, Manchester United .
Sally : Great ! I really like the team, too. What time is it going to be?
Sam : At three o'clock in the afternoon. I have two tickets here . Would You like to go with me ?
Sally :I'd love to . But I’m sorry I can't . We're going to have a basketball game tomorrow afternoon .
Sam : It doesn't matter(没关系) . Who are you going to play against（对抗）?
Sally : A team from No.2 Middle School .
Sam : Where are you going to play ?
Sally :In our school .
Sam : Good luck to you!
Sally :Thanks . Have a good time . See you later .
Sam :See you.