diff --git a/syntax/defer/main.go b/syntax/defer/main.go
index 607b010..8e1d562 100644
--- a/syntax/defer/main.go
+++ b/syntax/defer/main.go
@@ -24,7 +24,7 @@ func CatFile(path string) (err error) {
 			fmt.Println("Error Handling in defer called.")
 		}
 		// fileはCloseする必要がある。
-		file.Close()
+		err = file.Close()
 	}()
 
 	buf := make([]byte, 1024)
@@ -35,7 +35,7 @@ func CatFile(path string) (err error) {
 		}
 		if err != nil {
 			fmt.Println("File read error: ", err)
-			return
+			return err
 		}
 		fmt.Print(string(buf[:n]))
 	}
diff --git a/syntax/for/main.go b/syntax/for/main.go
index a6e91c3..06c1080 100644
--- a/syntax/for/main.go
+++ b/syntax/for/main.go
@@ -6,6 +6,7 @@ func main() {
 
 	numbers := make([]*int, 0, 3)
 	for i := 0; i < 3; i++ {
+		i := i
 		numbers = append(numbers, &i)
 	}
 
diff --git a/syntax/map/main.go b/syntax/map/main.go
index 687115c..92abb0b 100644
--- a/syntax/map/main.go
+++ b/syntax/map/main.go
@@ -1,6 +1,9 @@
 package main
 
-import "fmt"
+import (
+	"fmt"
+	"sort"
+)
 
 func main() {
 	// mapが参照型である事の確認
@@ -21,12 +24,22 @@ func main() {
 		2: "佐藤",
 		4: "佐々木",
 	}
+	keys := make([]int, 0, len(studnetIDMap))
+	for k := range studnetIDMap {
+		keys = append(keys, k)
+	}
 
-	for k, v := range studnetIDMap {
+	sort.Ints(keys)
+	for _, k := range keys {
 		// fmt.Printfでフォーマットに従った文字列を標準出力に出せる
+		fmt.Printf("Name of StudentID:%d is %s\n", k, studnetIDMap[k])
+	}
+}
+
 func addMap(m map[string]string) {
 	m["a"] = "あ"
 }
+
 func addMapWithCopy(m map[string]string) {
 	copied := make(map[string]string)
 	for k, v := range m {
diff --git a/syntax/pointer/main.go b/syntax/pointer/main.go
index 8da970d..9d84f77 100644
--- a/syntax/pointer/main.go
+++ b/syntax/pointer/main.go
@@ -18,8 +18,10 @@ func main() {
 }
 
 func increment(n int) int {
+	fmt.Printf("the address of n is %v\n", &n)
 	return n + 1
 }
 func incrementWithPointer(n *int) {
+	fmt.Printf("the address of n is %v\n", &n)
 	*n++
 }