diff --git a/Assignment4.md b/Assignment4.md
index ef79b8b..ef3d0e2 100644
--- a/Assignment4.md
+++ b/Assignment4.md
@@ -188,7 +188,7 @@ sudo docker pull wordpress
 > 你也可以登录ucloud镜像库并下载wordpress镜像，速度会快很多
 
 ```
-docker pull cloud_computing/wordpress
+sudo docker pull cloud_computing/wordpress
 ```
 
 <kbd>