随着人们生活节奏的加快，方便的小包装食品已被广泛接受。为了延长食品的保持期，防止食品受潮及富脂食品氧化变质，在包装袋中应放入的化学物质是

如图，在△ABC中，点D，E，F分别是边BC，CA，AB的中点，使四边形AFDE为菱形，应添加的条件是____ （添加一个条件即可）．

   There is a new shopping mall(商场) near my school. It is very big. There are five floors（层） of shops and each floor is very big. There are lots of clothes shops, but only one sports shop. There are lots of restaurants（饭馆） on the top（顶部的） floor, you can eat different kinds of food from different countries（国家）. I like going to see a movie. The mall is a really good place to go. It is a good place to meet friends.