diff --git a/docs/book/09-Polymorphism.md b/docs/book/09-Polymorphism.md
index c865cea..95dabd2 100644
--- a/docs/book/09-Polymorphism.md
+++ b/docs/book/09-Polymorphism.md
@@ -1168,6 +1168,8 @@ SadActor
 
 纯粹的替代意味着派生类可以完美地替代基类，当使用它们时，完全不需要知道这些子类的信息。也就是说，基类可以接收任意发送给派生类的消息，因为它们具有完全相同的接口。只需将派生类向上转型，不要关注对象的具体类型。所有一切都可以通过多态处理。
 
+![](../images/1562409366638.png)
+
 按这种方式思考，似乎只有纯粹的“is - a”关系才是唯一明智的做法，其他任何设计只会导致混乱且注定失败。这其实也是个陷阱。一旦按这种方式开始思考，就会转而发现继承扩展接口（遗憾的是，extends 关键字似乎怂恿我们这么做）才是解决特定问题的完美方案。这可以称为“is - like - a” 关系，因为派生类就像是基类——它有着相同的基本接口，但还具有需要额外方法实现的其他特性：
 
 ![](../images/1562409366637.png)
diff --git a/docs/images/1561774164644.png b/docs/images/1561774164644.png
deleted file mode 100644
index 7444d9a..0000000
Binary files a/docs/images/1561774164644.png and /dev/null differ
diff --git a/docs/images/1562204648023.png b/docs/images/1562204648023.png
index 6f5041c..d11af64 100644
Binary files a/docs/images/1562204648023.png and b/docs/images/1562204648023.png differ
diff --git a/docs/images/1562252767216.png b/docs/images/1562252767216.png
index f931261..e3b63ba 100644
Binary files a/docs/images/1562252767216.png and b/docs/images/1562252767216.png differ
diff --git a/docs/images/1562406479787.png b/docs/images/1562406479787.png
index 654348f..8f63b72 100644
Binary files a/docs/images/1562406479787.png and b/docs/images/1562406479787.png differ
diff --git a/docs/images/1562409366637.png b/docs/images/1562409366637.png
index 3c266d5..8bf7a42 100644
Binary files a/docs/images/1562409366637.png and b/docs/images/1562409366637.png differ
diff --git a/docs/images/1562409366638.png b/docs/images/1562409366638.png
new file mode 100644
index 0000000..5996bf9
Binary files /dev/null and b/docs/images/1562409366638.png differ
diff --git a/docs/images/1562409926765.png b/docs/images/1562409926765.png
index 563632d..b79a4b1 100644
Binary files a/docs/images/1562409926765.png and b/docs/images/1562409926765.png differ