diff --git a/flag.go b/flag.go
index a9eaa53..4988887 100644
--- a/flag.go
+++ b/flag.go
@@ -7,12 +7,13 @@ import (
 )
 
 var (
+	version     bool
 	file_output string
 	file_input  []string
 )
 
-// http://www.network-science.de/ascii/
-// is there any better way to print logo? plz contact us
+// ascii img is build from http://www.network-science.de/ascii/
+// is there any better way to print logo? please contact us
 func print_logo() {
 	fmt.Print("__              ___                _       ___      \n" +
 		"/ _\\ ___  __ _  / __\\___  _ __ ___ | |__   / _ \\___  \n" +
@@ -31,16 +32,25 @@ func print_logo() {
 // \__/\___|\__, \____/\___/|_| |_| |_|_.__/\____/\___/
 //             |_|
 
+// is for cmd
 func dna_flag() {
 	flag.StringVar(&file_output, "o", "a.nex", "output file")
+	flag.BoolVar(&version, "v", false, "version")
 	flag.Usage = usage
 	flag.Parse()
+	if version {
+		fmt.Println("SeqCombGo version: SeqCombGo/0.0.1")
+		os.Exit(0)
+	}
 	file_input = flag.Args() // []string{"foo", "bar"}
 	// 这里应该加个判断，如果输入不符合，后面的正则会报错
+	if len(file_input) == 0 {
+		fmt.Println("please use it in right way! see -h for help")
+		os.Exit(0)
+	}
 	print_logo()
-	fmt.Println()
-	fmt.Println("[input  file:]", file_input)
-	fmt.Println("[output file:]", file_output)
+	fmt.Println("\n[import files:]", file_input)
+	fmt.Println("[export file :]", file_output)
 }
 
 func usage() {
diff --git a/mix.go b/mix.go
index 9f11796..38a4397 100644
--- a/mix.go
+++ b/mix.go
@@ -2,12 +2,15 @@ package main
 
 import "strings"
 
+// dna 的整合
+// comb of dna
 func fas_mix(sum_nex []dna, sum_charset []charset) (map[string][]string, int, int) {
-	// dna 的整合
-	// comb of dna
+	
 	ntax := 0
 	nchar := sum_charset[len(sum_charset)-1].To
+
 	sum_dna := make(map[string][]string)
+
 	for _, v := range sum_nex {
 		for k1 := range v.min {
 			_, has := sum_dna[k1]
@@ -24,7 +27,7 @@ func fas_mix(sum_nex []dna, sum_charset []charset) (map[string][]string, int, in
 					sum_dna[k2][k] = v1
 				} else {
 					sum_dna[k2][k] = strings.Repeat("?", v.count)
-					// 之前就没写错吗
+					// 之前就没写错吗？已修复
 				}
 			}
 		}