图书馆是确保消防安全的重要场所，据此判断图书馆不需要出现的图标是(       )
 
①            ②            ③              ④                 ⑤

如图，已知△ABC为等腰直角三角形，AC=BC=4，∠BCD=15°，P为CD上的动点，则|PA﹣PB|的最大值是（　　）

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    Look at this. What's this in English, do you know? Ah, it's a photo. Who's that in the photo? It's Li Yan. Li Yan is my good friend. She is a beautiful girl. Who's that? The boy in black? It's Jim. He is an English boy. He is very cool. He is my friend, too. We are all in Class 3,Grade 7. I like Jim and Li Yan.