diff --git a/practical_exercises/key_exercises/输入输出运算符重载.cpp b/practical_exercises/key_exercises/输入输出运算符重载.cpp
index e44834d..e901654 100644
--- a/practical_exercises/key_exercises/输入输出运算符重载.cpp
+++ b/practical_exercises/key_exercises/输入输出运算符重载.cpp
@@ -1,39 +1,41 @@
 /*
- ��һ������Ա��Sales�������ݳ�Ա������name������֤��id������age��
- ��������/��������ʵ�ֶ�Sales�����ݳ�Ա������������
-*/
-#include<iostream.h>
-#include<string.h>
+   有一销售人员类Sales，其数据成员有姓名name，身份证号id，年龄age。
+   重载输入/输出运算符实现对Sales类数据成员的输入和输出。
+ */
+#include<iostream>
+#include<cstring>
+using namespace std;
 class Sales{
-private:
-		char name[10];
-		char id[18];
-		int age;
-public:
-		Sales(char *Name,char *ID,int Age);
+        private:
+                char name[10];
+                char id[18];
+                int age;
+        public:
+                Sales(char *Name,char *ID,int Age);
 
-		friend	Sales &operator<<(ostream &os,Sales &s);	//������������
-		friend	Sales &operator>>(istream &is,Sales &s);	//�������������
+                friend  Sales &operator<<(ostream &os,Sales &s);        //重载输出运算符
+                friend  Sales &operator>>(istream &is,Sales &s);        //重载输入运算符
 };
 Sales::Sales(char *Name,char *ID,int Age) {
-		strcpy(name,Name);
-		strcpy(id,ID);
-		age=Age;
+        strcpy(name,Name);
+        strcpy(id,ID);
+        age=Age;
 }
 Sales& operator<<(ostream &os,Sales &s) {
-		os<<s.name<<"\t";                 			//�������
-		os<<s.id<<"\t";                    			//�������֤��
-		os<<s.age<<endl;                  			//�������
-		return s;
+        os<<s.name<<"\t";                                       //输出姓名
+        os<<s.id<<"\t";                                         //输出身份证号
+        os<<s.age<<endl;                                        //输出年龄
+        return s;
 }
 Sales &operator>>(istream &is,Sales &s) {
-		cout<<"�����Ա������������֤�ţ�����"<<endl;  				is>>s.name>>s.id>>s.age;                       	
-		return s;
+        cout<<"输入雇员的姓名，身份证号，年龄"<<endl;
+        is>>s.name>>s.id>>s.age;
+        return s;
 }
-void main(){
-		Sales s1("�ſ�","214198012111711",40);   		//L1
-		cout<<s1;                             			//L2
-		cout<<endl;                           				//L3
-		cin>>s1;                              				//L4
-		cout<<s1;                             				//L5
+int main(){
+        Sales s1("杜康","214198012111711",40);                  //L1
+        cout<<s1;                                               //L2
+        cout<<endl;                                                     //L3
+        cin>>s1;                                                        //L4
+        cout<<s1;                                                       //L5
 }