diff --git a/labcodes/lab2/kern/mm/pmm.c b/labcodes/lab2/kern/mm/pmm.c
index 9e4f338..af54731 100644
--- a/labcodes/lab2/kern/mm/pmm.c
+++ b/labcodes/lab2/kern/mm/pmm.c
@@ -417,7 +417,7 @@ page_remove_pte(pde_t *pgdir, uintptr_t la, pte_t *ptep) {
      *   PTE_P           0x001                   // page table/directory entry flags bit : Present
      */
 #if 0
-    if (0) {                      //(1) check if page directory is present
+    if (0) {                      //(1) check if this page table entry is present
         struct Page *page = NULL; //(2) find corresponding page to pte
                                   //(3) decrease page reference
                                   //(4) and free this page when page reference reachs 0
diff --git a/labcodes/lab3/kern/mm/pmm.c b/labcodes/lab3/kern/mm/pmm.c
index 3b63deb..77633f2 100644
--- a/labcodes/lab3/kern/mm/pmm.c
+++ b/labcodes/lab3/kern/mm/pmm.c
@@ -430,7 +430,7 @@ page_remove_pte(pde_t *pgdir, uintptr_t la, pte_t *ptep) {
      *   PTE_P           0x001                   // page table/directory entry flags bit : Present
      */
 #if 0
-    if (0) {                      //(1) check if page directory is present
+    if (0) {                      //(1) check if this page table entry is present
         struct Page *page = NULL; //(2) find corresponding page to pte
                                   //(3) decrease page reference
                                   //(4) and free this page when page reference reachs 0
diff --git a/labcodes/lab4/kern/mm/pmm.c b/labcodes/lab4/kern/mm/pmm.c
index 543e5e9..59c70d9 100644
--- a/labcodes/lab4/kern/mm/pmm.c
+++ b/labcodes/lab4/kern/mm/pmm.c
@@ -433,7 +433,7 @@ page_remove_pte(pde_t *pgdir, uintptr_t la, pte_t *ptep) {
      *   PTE_P           0x001                   // page table/directory entry flags bit : Present
      */
 #if 0
-    if (0) {                      //(1) check if page directory is present
+    if (0) {                      //(1) check if this page table entry is present
         struct Page *page = NULL; //(2) find corresponding page to pte
                                   //(3) decrease page reference
                                   //(4) and free this page when page reference reachs 0
diff --git a/labcodes/lab5/kern/mm/pmm.c b/labcodes/lab5/kern/mm/pmm.c
index cc3f28c..cb92075 100644
--- a/labcodes/lab5/kern/mm/pmm.c
+++ b/labcodes/lab5/kern/mm/pmm.c
@@ -433,7 +433,7 @@ page_remove_pte(pde_t *pgdir, uintptr_t la, pte_t *ptep) {
      *   PTE_P           0x001                   // page table/directory entry flags bit : Present
      */
 #if 0
-    if (0) {                      //(1) check if page directory is present
+    if (0) {                      //(1) check if this page table entry is present
         struct Page *page = NULL; //(2) find corresponding page to pte
                                   //(3) decrease page reference
                                   //(4) and free this page when page reference reachs 0
diff --git a/labcodes/lab6/kern/mm/pmm.c b/labcodes/lab6/kern/mm/pmm.c
index cc3f28c..cb92075 100644
--- a/labcodes/lab6/kern/mm/pmm.c
+++ b/labcodes/lab6/kern/mm/pmm.c
@@ -433,7 +433,7 @@ page_remove_pte(pde_t *pgdir, uintptr_t la, pte_t *ptep) {
      *   PTE_P           0x001                   // page table/directory entry flags bit : Present
      */
 #if 0
-    if (0) {                      //(1) check if page directory is present
+    if (0) {                      //(1) check if this page table entry is present
         struct Page *page = NULL; //(2) find corresponding page to pte
                                   //(3) decrease page reference
                                   //(4) and free this page when page reference reachs 0
diff --git a/labcodes/lab7/kern/mm/pmm.c b/labcodes/lab7/kern/mm/pmm.c
index cc3f28c..cb92075 100644
--- a/labcodes/lab7/kern/mm/pmm.c
+++ b/labcodes/lab7/kern/mm/pmm.c
@@ -433,7 +433,7 @@ page_remove_pte(pde_t *pgdir, uintptr_t la, pte_t *ptep) {
      *   PTE_P           0x001                   // page table/directory entry flags bit : Present
      */
 #if 0
-    if (0) {                      //(1) check if page directory is present
+    if (0) {                      //(1) check if this page table entry is present
         struct Page *page = NULL; //(2) find corresponding page to pte
                                   //(3) decrease page reference
                                   //(4) and free this page when page reference reachs 0
diff --git a/labcodes/lab8/kern/mm/pmm.c b/labcodes/lab8/kern/mm/pmm.c
index cc3f28c..cb92075 100644
--- a/labcodes/lab8/kern/mm/pmm.c
+++ b/labcodes/lab8/kern/mm/pmm.c
@@ -433,7 +433,7 @@ page_remove_pte(pde_t *pgdir, uintptr_t la, pte_t *ptep) {
      *   PTE_P           0x001                   // page table/directory entry flags bit : Present
      */
 #if 0
-    if (0) {                      //(1) check if page directory is present
+    if (0) {                      //(1) check if this page table entry is present
         struct Page *page = NULL; //(2) find corresponding page to pte
                                   //(3) decrease page reference
                                   //(4) and free this page when page reference reachs 0