diff --git a/TinySTL/Vector.h b/TinySTL/Vector.h
index 5a1d641..9b6a691 100644
--- a/TinySTL/Vector.h
+++ b/TinySTL/Vector.h
@@ -71,9 +71,10 @@ namespace TinySTL{
 		void shrink_to_fit();
 
 		//访问元素相关
-		value_type& operator[](const difference_type i){ return *(begin() + i); }
-		value_type& front(){ return *(begin()); }
-		value_type& back(){ return *(end() - 1); }
+		reference operator[](const difference_type i){ return *(begin() + i); }
+		const_reference operator[](const difference_type i)const{ return *(cbegin() + i); }
+		reference front(){ return *(begin()); }
+		reference back(){ return *(end() - 1); }
 		pointer data(){ return start_; }
 
 		//修改容器相关的操作