如图，AD是△ABC中∠BAC的平分线，DE⊥AB于点E，DF⊥AC交AC于点F．S_△ABC=7，DE=2，AB=4，则AC长是（　　）

某同学按如图所示对生物进行分类，下列选项中与图示中①②③代表的生物依次吻合的是（  ）

   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.

有关亚洲地形特征的说法正确的是（    ）