diff --git a/day10/src/com/inmind/poly08/Animal.java b/day10/src/com/inmind/poly08/Animal.java
index 9dc1e57..53fe914 100644
--- a/day10/src/com/inmind/poly08/Animal.java
+++ b/day10/src/com/inmind/poly08/Animal.java
@@ -9,6 +9,10 @@ public class Animal {
         System.out.println("动物跑");
     }
 
+    public void sleep(){
+        System.out.println("动物睡");
+    }
+
     public void getNumFu(){
         System.out.println(numFu);
     }
diff --git a/day10/src/com/inmind/poly08/Cat.java b/day10/src/com/inmind/poly08/Cat.java
index 3fc9a5d..6d7a0d0 100644
--- a/day10/src/com/inmind/poly08/Cat.java
+++ b/day10/src/com/inmind/poly08/Cat.java
@@ -8,6 +8,11 @@ public class Cat extends Animal{
         System.out.println("猫闪着跑，闪身步");
     }
 
+    @Override
+    public void sleep() {
+        System.out.println("猫卷着在猫窝上睡");
+    }
+
     public void getNumZi(){
         System.out.println(numZi);
     }
diff --git a/day10/src/com/inmind/poly08/Demo09.java b/day10/src/com/inmind/poly08/Demo09.java
new file mode 100644
index 0000000..73710a4
--- /dev/null
+++ b/day10/src/com/inmind/poly08/Demo09.java
@@ -0,0 +1,31 @@
+package com.inmind.poly08;
+/*
+多态的核心好处：“以不变，应万变”---通过抽象定义统一接口，应对具体实现的变化。它让代码简洁，灵活，更容易扩展。
+ */
+public class Demo09 {
+    public static void main(String[] args) {
+        //让狗和猫，或其他一些动物，去展示跑，睡的行为
+        Dog dog = new Dog();
+        /*dog.run();
+        dog.sleep();*/
+        show(dog);
+        Cat cat = new Cat();
+        /*cat.run();
+        cat.sleep();*/
+        show(cat);
+    }
+
+    //封装一个方法来调用动物跑和睡的行为
+    public static void show(Animal animal) {//多态的好处！！！！！
+        animal.run();
+        animal.sleep();
+    }
+    /*public static void show(Dog dog) {
+        dog.run();
+        dog.sleep();
+    }
+    public static void show(Cat cat) {
+        cat.run();
+        cat.sleep();
+    }*/
+}
diff --git a/day10/src/com/inmind/poly08/Dog.java b/day10/src/com/inmind/poly08/Dog.java
index cbe937a..f0e83b1 100644
--- a/day10/src/com/inmind/poly08/Dog.java
+++ b/day10/src/com/inmind/poly08/Dog.java
@@ -5,4 +5,9 @@ public class Dog extends Animal{
     public void run() {
         System.out.println("狗哆嗦地跑");
     }
+
+    @Override
+    public void sleep() {
+        System.out.println("狗在大街上四脚朝天睡");
+    }
 }