diff --git a/CFree/▼配套习题解析/▼06 树和二叉树/▼习题测试文档-06/Data/Algo_6_51.txt b/CFree/▼配套习题解析/▼06 树和二叉树/▼习题测试文档-06/Data/Algo_6_51.txt
index be56cc6..759451e 100644
--- a/CFree/▼配套习题解析/▼06 树和二叉树/▼习题测试文档-06/Data/Algo_6_51.txt	
+++ b/CFree/▼配套习题解析/▼06 树和二叉树/▼习题测试文档-06/Data/Algo_6_51.txt	
@@ -1 +1 @@
-��������*/*+a^^b^^-c^^d^^e^^-g^^h^^
\ No newline at end of file
+��������*/-+a^^b^^-c^^d^^e^^-g^^h^^
\ No newline at end of file
diff --git a/CFree/▼配套习题解析/▼06 树和二叉树/▼习题测试文档-06/Question-6.51-main.c b/CFree/▼配套习题解析/▼06 树和二叉树/▼习题测试文档-06/Question-6.51-main.c
index 25016d9..379a2c2 100644
--- a/CFree/▼配套习题解析/▼06 树和二叉树/▼习题测试文档-06/Question-6.51-main.c	
+++ b/CFree/▼配套习题解析/▼06 树和二叉树/▼习题测试文档-06/Question-6.51-main.c	
@@ -5,7 +5,6 @@
 /* ����ԭ�� */
 void Algo_6_51(BiTree T);
 Status IsOperator_6_51(char c);
-Status LowPriority_6_51(char a, char b);
 
 int main(int argc, char *argv[])
 {
@@ -38,9 +37,10 @@ void Algo_6_51(BiTree T)
 	if(T)
 	{
 		if(T->lchild)
-		{					
-			if(IsOperator_6_51(T->lchild->data) && LowPriority_6_51(T->lchild->data, T->data))
-			{				//��ǰ���������Dz����������ȼ����ڵ�ǰ��� 
+		{	
+			// �������DZ���ʽ������������			
+			if(IsOperator_6_51(T->lchild->data))
+			{
 				printf("(");
 				Algo_6_51(T->lchild);
 				printf(")");
@@ -53,8 +53,9 @@ void Algo_6_51(BiTree T)
 		
 		if(T->rchild)
 		{
-			if(IsOperator_6_51(T->rchild->data) && LowPriority_6_51(T->rchild->data, T->data))
-			{				//��ǰ�����Һ����Dz����������ȼ����ڵ�ǰ���
+			// �������DZ���ʽ������������
+			if(IsOperator_6_51(T->rchild->data))
+			{
 				printf("(");
 				Algo_6_51(T->rchild);
 				printf(")");
@@ -72,11 +73,3 @@ Status IsOperator_6_51(char c)				//
 	else
 		return ERROR;
 } 
-
-Status LowPriority_6_51(char a, char b)		//ȷ��������a�����ȼ��Ƿ����b 
-{
-	if((a=='+' || a=='-') && (b=='*' || b=='/'))
-		return TRUE;
-	else									//a��bͬ�ȼ�ʱҲ��Ϊa�����ȼ��ϸ� 
-		return ERROR;
-}
diff --git a/CLion/ExerciseBook/06.51/06.51.c b/CLion/ExerciseBook/06.51/06.51.c
index 5b3809d..c7418f6 100644
--- a/CLion/ExerciseBook/06.51/06.51.c
+++ b/CLion/ExerciseBook/06.51/06.51.c
@@ -10,9 +10,6 @@ void Algo_6_51(BiTree T);
 // 判断字符c是否为操作符
 Status IsOperator(char c);
 
-// 判断两个操作符的优先级
-Status Priority(char a, char b);
-
 
 int main(int argc, char* argv[]) {
     BiTree T;
@@ -40,8 +37,8 @@ void Algo_6_51(BiTree T) {
     }
     
     if(T->lchild != NULL) {
-        // 当前结点的左孩子是操作符且优先级低于当前结点
-        if(IsOperator(T->lchild->data) && Priority(T->lchild->data, T->data) < 0) {
+        // 左子树是表达式，则添加括号
+        if(IsOperator(T->lchild->data)) {
             printf("(");
             Algo_6_51(T->lchild);
             printf(")");
@@ -53,8 +50,8 @@ void Algo_6_51(BiTree T) {
     printf("%c", T->data);
     
     if(T->rchild != NULL) {
-        // 当前结点的右孩子是操作符且优先级低于当前结点
-        if(IsOperator(T->rchild->data) && Priority(T->rchild->data, T->data) < 0) {
+        // 右子树是表达式，则添加括号
+        if(IsOperator(T->rchild->data)) {
             printf("(");
             Algo_6_51(T->rchild);
             printf(")");
@@ -72,19 +69,3 @@ Status IsOperator(char c) {
         return ERROR;
     }
 }
-
-// 判断两个操作符的优先级
-Status Priority(char a, char b) {
-    // a的优先级低
-    if((a == '+' || a == '-') && (b == '*' || b == '/')) {
-        return -1;
-        
-        // a的优先级高
-    } else if((a == '*' || a == '/') && (b == '+' || b == '-')) {
-        return 1;
-        
-        // 优先级相同
-    } else {
-        return 0;
-    }
-}
diff --git a/CLion/ExerciseBook/06.51/TestData.txt b/CLion/ExerciseBook/06.51/TestData.txt
index e664c85..9c3cccb 100644
--- a/CLion/ExerciseBook/06.51/TestData.txt
+++ b/CLion/ExerciseBook/06.51/TestData.txt
@@ -1 +1 @@
-先序序列→*/*+a^^b^^-c^^d^^e^^-g^^h^^
\ No newline at end of file
+先序序列→*/-+a^^b^^-c^^d^^e^^-g^^h^^
\ No newline at end of file
diff --git a/Dev-C++/ExerciseBook/06.51/06.51.cpp b/Dev-C++/ExerciseBook/06.51/06.51.cpp
index eb334e8..a38c29f 100644
--- a/Dev-C++/ExerciseBook/06.51/06.51.cpp
+++ b/Dev-C++/ExerciseBook/06.51/06.51.cpp
@@ -10,23 +10,20 @@ void Algo_6_51(BiTree T);
 // �ж��ַ�c�Ƿ�Ϊ������
 Status IsOperator(char c);
 
-// �ж����������������ȼ�
-Status Priority(char a, char b);
-
 
 int main(int argc, char* argv[]) {
     BiTree T;
-    
+
     printf("��������������������T...\n");
     InitBiTree(&T);
     CreateBiTree(&T, "TestData.txt");
     PrintTree(T);
     printf("\n");
-    
+
     printf("�����������ʽ��");
     Algo_6_51(T);
     printf("\n");
-    
+
     return 0;
 }
 
@@ -38,10 +35,10 @@ void Algo_6_51(BiTree T) {
     if(T == NULL) {
         return;
     }
-    
+
     if(T->lchild != NULL) {
-        // ��ǰ���������Dz����������ȼ����ڵ�ǰ���
-        if(IsOperator(T->lchild->data) && Priority(T->lchild->data, T->data) < 0) {
+        // �������DZ���ʽ������������
+        if(IsOperator(T->lchild->data)) {
             printf("(");
             Algo_6_51(T->lchild);
             printf(")");
@@ -49,12 +46,12 @@ void Algo_6_51(BiTree T) {
             Algo_6_51(T->lchild);
         }
     }
-    
+
     printf("%c", T->data);
-    
+
     if(T->rchild != NULL) {
-        // ��ǰ�����Һ����Dz����������ȼ����ڵ�ǰ���
-        if(IsOperator(T->rchild->data) && Priority(T->rchild->data, T->data) < 0) {
+        // �������DZ���ʽ������������
+        if(IsOperator(T->rchild->data)) {
             printf("(");
             Algo_6_51(T->rchild);
             printf(")");
@@ -73,18 +70,3 @@ Status IsOperator(char c) {
     }
 }
 
-// �ж����������������ȼ�
-Status Priority(char a, char b) {
-    // a�����ȼ���
-    if((a == '+' || a == '-') && (b == '*' || b == '/')) {
-        return -1;
-        
-        // a�����ȼ���
-    } else if((a == '*' || a == '/') && (b == '+' || b == '-')) {
-        return 1;
-        
-        // ���ȼ���ͬ
-    } else {
-        return 0;
-    }
-}
diff --git a/Dev-C++/ExerciseBook/06.51/TestData.txt b/Dev-C++/ExerciseBook/06.51/TestData.txt
index e53e33a..667d916 100644
--- a/Dev-C++/ExerciseBook/06.51/TestData.txt
+++ b/Dev-C++/ExerciseBook/06.51/TestData.txt
@@ -1 +1 @@
-��������*/*+a^^b^^-c^^d^^e^^-g^^h^^
+��������*/-+a^^b^^-c^^d^^e^^-g^^h^^
diff --git a/VisualC++/ExerciseBook/06.51/06.51.c b/VisualC++/ExerciseBook/06.51/06.51.c
index eb334e8..cb1fba3 100644
--- a/VisualC++/ExerciseBook/06.51/06.51.c
+++ b/VisualC++/ExerciseBook/06.51/06.51.c
@@ -10,9 +10,6 @@ void Algo_6_51(BiTree T);
 // �ж��ַ�c�Ƿ�Ϊ������
 Status IsOperator(char c);
 
-// �ж����������������ȼ�
-Status Priority(char a, char b);
-
 
 int main(int argc, char* argv[]) {
     BiTree T;
@@ -40,8 +37,8 @@ void Algo_6_51(BiTree T) {
     }
     
     if(T->lchild != NULL) {
-        // ��ǰ���������Dz����������ȼ����ڵ�ǰ���
-        if(IsOperator(T->lchild->data) && Priority(T->lchild->data, T->data) < 0) {
+        // �������DZ���ʽ������������
+        if(IsOperator(T->lchild->data)) {
             printf("(");
             Algo_6_51(T->lchild);
             printf(")");
@@ -53,8 +50,8 @@ void Algo_6_51(BiTree T) {
     printf("%c", T->data);
     
     if(T->rchild != NULL) {
-        // ��ǰ�����Һ����Dz����������ȼ����ڵ�ǰ���
-        if(IsOperator(T->rchild->data) && Priority(T->rchild->data, T->data) < 0) {
+        // �������DZ���ʽ������������
+        if(IsOperator(T->rchild->data)) {
             printf("(");
             Algo_6_51(T->rchild);
             printf(")");
@@ -72,19 +69,3 @@ Status IsOperator(char c) {
         return ERROR;
     }
 }
-
-// �ж����������������ȼ�
-Status Priority(char a, char b) {
-    // a�����ȼ���
-    if((a == '+' || a == '-') && (b == '*' || b == '/')) {
-        return -1;
-        
-        // a�����ȼ���
-    } else if((a == '*' || a == '/') && (b == '+' || b == '-')) {
-        return 1;
-        
-        // ���ȼ���ͬ
-    } else {
-        return 0;
-    }
-}
diff --git a/VisualC++/ExerciseBook/06.51/TestData.txt b/VisualC++/ExerciseBook/06.51/TestData.txt
index be56cc6..759451e 100644
--- a/VisualC++/ExerciseBook/06.51/TestData.txt
+++ b/VisualC++/ExerciseBook/06.51/TestData.txt
@@ -1 +1 @@
-��������*/*+a^^b^^-c^^d^^e^^-g^^h^^
\ No newline at end of file
+��������*/-+a^^b^^-c^^d^^e^^-g^^h^^
\ No newline at end of file
diff --git a/VisualC++/ExerciseBook/ExerciseBook.sdf b/VisualC++/ExerciseBook/ExerciseBook.sdf
index ca2ffc6..9b2851f 100644
Binary files a/VisualC++/ExerciseBook/ExerciseBook.sdf and b/VisualC++/ExerciseBook/ExerciseBook.sdf differ
diff --git a/VisualC++/ExerciseBook/ExerciseBook.suo b/VisualC++/ExerciseBook/ExerciseBook.suo
index 1fb1202..fa4c2ab 100644
Binary files a/VisualC++/ExerciseBook/ExerciseBook.suo and b/VisualC++/ExerciseBook/ExerciseBook.suo differ