diff --git a/src/class06/Code03_SmallerEqualBigger.java b/src/class06/Code03_SmallerEqualBigger.java
index d234365..a5718ed 100644
--- a/src/class06/Code03_SmallerEqualBigger.java
+++ b/src/class06/Code03_SmallerEqualBigger.java
@@ -101,8 +101,10 @@ public class Code03_SmallerEqualBigger {
 			sT.next = eH;
 			eT = eT == null ? sT : eT; // 下一步，谁去连大于区域的头，谁就变成eT
 		}
-		// 上面的if，不管跑了没有，et
-		// all reconnect
+		// 下一步，一定是需要用eT 去接 大于区域的头
+		// 有等于区域，eT -> 等于区域的尾结点
+		// 无等于区域，eT -> 小于区域的尾结点
+		// eT 尽量不为空的尾巴节点
 		if (eT != null) { // 如果小于区域和等于区域，不是都没有
 			eT.next = mH;
 		}
diff --git a/src/class06/Code04_CopyListWithRandom.java b/src/class06/Code04_CopyListWithRandom.java
index 5937492..0a0a836 100644
--- a/src/class06/Code04_CopyListWithRandom.java
+++ b/src/class06/Code04_CopyListWithRandom.java
@@ -15,6 +15,8 @@ public class Code04_CopyListWithRandom {
 	}
 
 	public static Node copyListWithRand1(Node head) {
+		// key 老节点
+		// value 新节点
 		HashMap<Node, Node> map = new HashMap<Node, Node>();
 		Node cur = head;
 		while (cur != null) {
@@ -25,6 +27,7 @@ public class Code04_CopyListWithRandom {
 		while (cur != null) {
 			// cur 老
 			// map.get(cur) 新
+			// 新.next ->  cur.next克隆节点找到
 			map.get(cur).next = map.get(cur.next);
 			map.get(cur).rand = map.get(cur.rand);
 			cur = cur.next;
diff --git a/src/class06/Code05_FindFirstIntersectNode.java b/src/class06/Code05_FindFirstIntersectNode.java
index 40eb34e..bc27bbb 100644
--- a/src/class06/Code05_FindFirstIntersectNode.java
+++ b/src/class06/Code05_FindFirstIntersectNode.java
@@ -32,21 +32,22 @@ public class Code05_FindFirstIntersectNode {
 			return null;
 		}
 		// n1 慢  n2 快
-		Node n1 = head.next; // n1 -> slow
-		Node n2 = head.next.next; // n2 -> fast
-		while (n1 != n2) {
-			if (n2.next == null || n2.next.next == null) {
+		Node slow = head.next; // n1 -> slow
+		Node fast = head.next.next; // n2 -> fast
+		while (slow != fast) {
+			if (fast.next == null || fast.next.next == null) {
 				return null;
 			}
-			n2 = n2.next.next;
-			n1 = n1.next;
+			fast = fast.next.next;
+			slow = slow.next;
 		}
-		n2 = head; // n2 -> walk again from head
-		while (n1 != n2) {
-			n1 = n1.next;
-			n2 = n2.next;
+		// slow fast  相遇
+		fast = head; // n2 -> walk again from head
+		while (slow != fast) {
+			slow = slow.next;
+			fast = fast.next;
 		}
-		return n1;
+		return slow;
 	}
 
 	// 如果两个链表都无环，返回第一个相交节点，如果不想交，返回null
diff --git a/src/class06/Test.java b/src/class06/Test.java
index 831e8d6..f833821 100644
--- a/src/class06/Test.java
+++ b/src/class06/Test.java
@@ -2,25 +2,4 @@ package class06;
 
 public class Test {
 
-	public static class Node{
-		public int value;
-		public Node next;
-		public Node(int v) {
-			value = v;
-		}
-	}
-	
-	public static void main(String[] args) {
-		Node a = new Node(1);
-		Node b = new Node(2);
-		Node c = new Node(3);
-		
-		a.next = b;
-		b.next = c;
-		
-		c = null;
-		
-	}
-	
-	
 }
diff --git a/src/class07/Code02_UnRecursiveTraversalBT.java b/src/class07/Code02_UnRecursiveTraversalBT.java
index ddff515..277e96b 100644
--- a/src/class07/Code02_UnRecursiveTraversalBT.java
+++ b/src/class07/Code02_UnRecursiveTraversalBT.java
@@ -33,18 +33,18 @@ public class Code02_UnRecursiveTraversalBT {
 		System.out.println();
 	}
 
-	public static void in(Node head) {
+	public static void in(Node cur) {
 		System.out.print("in-order: ");
-		if (head != null) {
+		if (cur != null) {
 			Stack<Node> stack = new Stack<Node>();
-			while (!stack.isEmpty() || head != null) {
-				if (head != null) {
-					stack.push(head);
-					head = head.left;
+			while (!stack.isEmpty() || cur != null) {
+				if (cur != null) {
+					stack.push(cur);
+					cur = cur.left;
 				} else {
-					head = stack.pop();
-					System.out.print(head.value + " ");
-					head = head.right;
+					cur = stack.pop();
+					System.out.print(cur.value + " ");
+					cur = cur.right;
 				}
 			}
 		}
@@ -58,7 +58,7 @@ public class Code02_UnRecursiveTraversalBT {
 			Stack<Node> s2 = new Stack<Node>();
 			s1.push(head);
 			while (!s1.isEmpty()) {
-				head = s1.pop();
+				head = s1.pop(); // 头 右 左
 				s2.push(head);
 				if (head.left != null) {
 					s1.push(head.left);
@@ -67,6 +67,7 @@ public class Code02_UnRecursiveTraversalBT {
 					s1.push(head.right);
 				}
 			}
+			// 左 右 头
 			while (!s2.isEmpty()) {
 				System.out.print(s2.pop().value + " ");
 			}