diff --git a/problems/0701.二叉搜索树中的插入操作.md b/problems/0701.二叉搜索树中的插入操作.md
index 6a78b2b4..a6f932b0 100644
--- a/problems/0701.二叉搜索树中的插入操作.md
+++ b/problems/0701.二叉搜索树中的插入操作.md
@@ -331,9 +331,8 @@ class Solution:
 ```
 
 **递归法** - 无返回值 有注释 不用Helper function
-```
+```python
 class Solution:
-    last = None
     def insertIntoBST(self, root: Optional[TreeNode], val: int) -> Optional[TreeNode]:
         if not root:    # for root==None
             return TreeNode(val)