diff --git a/w6/AnimalSystem.java b/w6/AnimalSystem.java
new file mode 100644
index 0000000..e898f32
--- /dev/null
+++ b/w6/AnimalSystem.java
@@ -0,0 +1,66 @@
+// 抽象类 Animal
+abstract class Animal {
+    public abstract void makeSound();
+}
+
+// 接口 Swimmable
+interface Swimmable {
+    void swim();
+}
+
+// Dog 类继承 Animal 并实现 Swimmable
+class Dog extends Animal implements Swimmable {
+    @Override
+    public void makeSound() {
+        System.out.println("狗叫：汪汪汪！");
+    }
+    
+    @Override
+    public void swim() {
+        System.out.println("狗会游泳，正在狗刨式前进...");
+    }
+}
+
+// Cat 类继承 Animal，不实现 Swimmable
+class Cat extends Animal {
+    @Override
+    public void makeSound() {
+        System.out.println("猫叫：喵喵喵～");
+    }
+}
+
+// 测试主类
+public class AnimalSystem {
+    public static void main(String[] args) {
+        // 多态调用：父类引用指向子类对象
+        Animal dog = new Dog();
+        Animal cat = new Cat();
+        
+        System.out.println("===== 动物叫声系统 =====");
+        dog.makeSound();
+        cat.makeSound();
+        
+        System.out.println("\n===== 游泳测试 =====");
+        // Dog 实现了 Swimmable，可以调用 swim()
+        if (dog instanceof Swimmable) {
+            ((Swimmable) dog).swim();
+        }
+        
+        // Cat 没有实现 Swimmable，不能调用 swim()
+        if (cat instanceof Swimmable) {
+            ((Swimmable) cat).swim();
+        } else {
+            System.out.println("猫不会游泳，所以不能调用 swim() 方法");
+        }
+        
+        System.out.println("\n===== 完整多态演示 =====");
+        // 使用 Swimmable 接口类型引用 Dog 对象
+        Swimmable swimmableDog = new Dog();
+        swimmableDog.swim();
+        
+        // 验证 Dog 和 Cat 的类型
+        System.out.println("\ndog 是 Dog 的实例？" + (dog instanceof Dog));
+        System.out.println("dog 是 Swimmable 的实例？" + (dog instanceof Swimmable));
+        System.out.println("cat 是 Swimmable 的实例？" + (cat instanceof Swimmable));
+    }
+}
\ No newline at end of file
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