下列器官中，与食物接触面积最大的是（　　）

    There is a zoo near my house. I like ____  there. There are many ____  in it.
    Look! There is a koala ____  the tree. Isn’t he ____ ? Under the tree, there is a ____ . Her neck(脖子) is so long. She is a lovely girl. ____  is the panada? She is eating the bamboo(竹子). She's ____  shy. But the elephant is interesting. He is playing with kids with his____ nose. They are very funny. Look! In the pool, there are two dolphins. They are playing with ____  balls. ____  happy they are !

若将绿藻甲、乙、丙、丁甲组分别放置于：湖泊、100m深的海中、800m深的海中，50m深的海中，首先死亡的是生活在何处的绿藻？（　　）

设m＞n＞0，m²+n²=6mn，则$\frac{m^2-n^2}{mn}$=（　　）

根据汉语意思用英语完成句子，将答案写在横线上。