diff --git a/balloon/abstract_syntax_tree.cpp b/balloon/abstract_syntax_tree.cpp
index 8dae46d..cf853b1 100644
--- a/balloon/abstract_syntax_tree.cpp
+++ b/balloon/abstract_syntax_tree.cpp
@@ -4,8 +4,9 @@
 
 
 int exit_type=0;
-std::stack<var> ret_stack;// for function ret use
-std::list<var> parameter;// for function call use
+std::stack<var> ret_stack; // for function ret use
+std::list<var> parameter;  // for function call use
+
 
 var abstract_syntax_tree::calculation()
 {
@@ -30,12 +31,23 @@ var abstract_syntax_tree::calculation()
 	}
 	else if(this->type==__array)
 	{
-		temp=this->array_generation();
+		temp.set_type(__var_array);
+		if(!children.empty())
+			for(std::list<abstract_syntax_tree>::iterator i=children.begin();i!=children.end();++i)
+				temp.append_array(i->calculation());
 		return temp;
 	}
 	else if(this->type==__hash)
 	{
-		temp=this->hash_generation();
+		temp.set_type(__var_hash);
+		if(!children.empty())
+			for(std::list<abstract_syntax_tree>::iterator i=children.begin();i!=children.end();++i)
+			{
+				var t;
+				t=i->children.front().calculation();
+				t.set_name(i->name);
+				temp.append_hash(t);
+			}
 		return temp;
 	}
 	else if(this->type==__function)
@@ -477,31 +489,6 @@ var abstract_syntax_tree::call_identifier()
 	return temp;
 }
 
-var abstract_syntax_tree::array_generation()
-{
-	var new_var;
-	new_var.set_type(__var_array);
-	if(!children.empty())
-		for(std::list<abstract_syntax_tree>::iterator i=children.begin();i!=children.end();++i)
-			new_var.append_array(i->calculation());
-	return new_var;
-}
-
-var abstract_syntax_tree::hash_generation()
-{
-	var new_var;
-	new_var.set_type(__var_hash);
-	if(!children.empty())
-		for(std::list<abstract_syntax_tree>::iterator i=children.begin();i!=children.end();++i)
-		{
-			var temp;
-			temp=i->children.front().calculation();
-			temp.set_name(i->name);
-			new_var.append_hash(temp);
-		}
-	return new_var;
-}
-
 var* abstract_syntax_tree::get_var_addr()
 {
 	var* addr=&error_var;
@@ -697,6 +684,8 @@ void abstract_syntax_tree::run_root()
 	}
 	end_time=time(NULL);
 	std::cout<<"------------------------------------------------------------------------------"<<std::endl;
+	if(exit_type!=__process_exited_successfully)
+		alert_sound();
 	std::cout<<">>[Runtime] process exited after "<<end_time-beg_time<<" sec(s) with returned state \'";
 	print_exit_type(exit_type);
 	std::cout<<"\'."<<std::endl;
diff --git a/balloon/abstract_syntax_tree.h b/balloon/abstract_syntax_tree.h
index 6ba54e8..da057b0 100644
--- a/balloon/abstract_syntax_tree.h
+++ b/balloon/abstract_syntax_tree.h
@@ -201,8 +201,6 @@ class abstract_syntax_tree
 		var calculation();
 		bool condition_check();
 		var call_identifier();
-		var array_generation();
-		var hash_generation();
 		var* get_var_addr();
 		var assignment();
 		void run_root();
diff --git a/balloon/balloon.h b/balloon/balloon.h
index e9d6efa..24bda53 100644
--- a/balloon/balloon.h
+++ b/balloon/balloon.h
@@ -1,6 +1,16 @@
 #ifndef __BALLOON_H__
 #define __BALLOON_H__
 
+/*
+	Balloon language made by ValKmjolnir
+	place: NUAA QQ: 896693328 e-mail: 896693328@qq.com
+	Balloon is a real subset of Nasal language
+	Nasal language is created for FlightGear
+	Nasal language seems like ECMAscript
+	So you may find some similarities between nas & js
+*/
+
+
 #include <iostream>
 #include <cstdlib>
 #include <cstring>
@@ -10,13 +20,34 @@
 #include <stack>
 #include <ctime>
 
-#include "balloon_type.h"
-#include "abstract_syntax_tree.h"
-#include "balloon_var.h"
-#include "balloon_lexer.h"
-#include "balloon_parse.h"
-#include "balloon_scope.h"
-
-#include "abstract_syntax_tree.cpp"
+void alert_sound()
+{
+	printf("\a");
+	return;
+}
 
+#include "balloon_type.h"                 // place some enums
+#include "abstract_syntax_tree.h"         // ast
+#include "balloon_var.h"                  // var
+/* global varia in balloon_var.h :
+	var error_var;                        // give an error_var to get 
+*/
+#include "balloon_lexer.h"                // lexer
+/* global varia in balloon_lexer.h :
+	struct token;                         // used to get token from resource codes
+	std::string reserve_word[15];         // place many reserve words
+	int is_reserve_word(std::string str); // check the string is a reserve word or not and return the number of reserve word
+	bool check_number(std::string str);   // check the string can be processed to number or not
+*/
+#include "balloon_parse.h"                // parser
+#include "balloon_scope.h"                // place to store vars
+/* global varia in balloon_scope.h :
+	balloon_scope scope;                  // make a place to vars
+*/
+#include "abstract_syntax_tree.cpp"       // runtime
+/* global varia in abstract_syntax_tree.cpp :
+	int exit_type;                        // record the state of runtime
+	std::stack<var> ret_stack;            // for function ret use
+	std::list<var> parameter;             // for function call use
+*/
 #endif
diff --git a/balloon/balloon_lexer.h b/balloon/balloon_lexer.h
index dcb6ca4..79b124f 100644
--- a/balloon/balloon_lexer.h
+++ b/balloon/balloon_lexer.h
@@ -1,12 +1,17 @@
 #ifndef __BALLOON_LEXER_H__
 #define __BALLOON_LEXER_H__
 
+/*
+	reserve words are those below
+	and they are also the reserve words of nasal
+*/
 std::string reserve_word[15]=
 {
 	"for","foreach","forindex","while",
 	"var","func","break","continue","return",
 	"if","else","elsif","nil","and","or"
 };
+
 int is_reserve_word(std::string str)
 {
 	for(int i=0;i<15;++i)
@@ -14,6 +19,10 @@ int is_reserve_word(std::string str)
 			return __reserve_word;
 	return __token_identifier;
 }
+
+/*
+	check if the generated string can be put to number
+*/
 bool check_number(std::string str)
 {
 	if(str.length()==1)
@@ -63,7 +72,12 @@ bool check_number(std::string str)
 	return false;
 }
 
-
+/*
+	use std::list<char> to store resource codes
+	and if you continue adding files
+	the codes will be added behind files that have
+	been added in before
+*/
 class resource_file
 {
 	private:
@@ -108,6 +122,8 @@ class resource_file
 			{
 				if(32<=*i && *i<128 || *i=='\n')
 					std::cout<<*i;
+				else if(*i=='\t')
+					std::cout<<"    ";
 				if(*i=='\n')
 				{
 					++line;
@@ -125,7 +141,15 @@ struct token
 	int type;
 	std::string str;
 };
-
+/*
+	lexer can recognize:
+		number: 100(int) 0.001(double) 0xdeadbeef(hex) 0o1701(oct)
+		string: "str" 'str'
+		identifier
+			reserve word
+			normal identifier: ID and id is different
+		operator
+*/
 class balloon_lexer
 {
 	private:
diff --git a/balloon/balloon_parse.h b/balloon/balloon_parse.h
index a518fd6..5e5e09d 100644
--- a/balloon/balloon_parse.h
+++ b/balloon/balloon_parse.h
@@ -81,26 +81,58 @@ class balloon_parse
 			root.run_root();
 			return;
 		}
+		/*
+			ret: return expression
+			choose: if-else expression
+			loop: while/for/forindex/foreach expression
+			definition
+			assignment
+			block: set of expressions
+			generate:
+				array
+				hash
+				number
+				string
+				function
+			block
+			scalar:
+				calculation:
+				calculation_or:
+				calculation_and:
+				calculation_cmp:
+				calculation_additive:
+				calculation_multive:
+					call_identifier
+					unary expression
+					->generate
+			semi: check if the statements is ended with semi
+			parse_main: main process
+		*/
 		abstract_syntax_tree ret();
 		abstract_syntax_tree choose();
 		abstract_syntax_tree loop();
 		abstract_syntax_tree definition();
 		abstract_syntax_tree assignment();
+		abstract_syntax_tree block();
+		
 		abstract_syntax_tree array_generate();
 		abstract_syntax_tree hash_generate();
+		abstract_syntax_tree func_generate();
 		abstract_syntax_tree check_number();
 		abstract_syntax_tree check_string();
-		abstract_syntax_tree check_unary();
-		abstract_syntax_tree block();
-		abstract_syntax_tree func_generate();
+		
+		abstract_syntax_tree scalar();
+		
 		abstract_syntax_tree call_identifier();
+		abstract_syntax_tree check_unary();
+		
 		abstract_syntax_tree calculation();
 		abstract_syntax_tree calculation_or();
 		abstract_syntax_tree calculation_and();
 		abstract_syntax_tree calculation_cmp();
 		abstract_syntax_tree calculation_additive();
 		abstract_syntax_tree calculation_multive();
-		abstract_syntax_tree scalar();
+		
 		void check_semi();
 		void parse_main();
 };
@@ -489,7 +521,7 @@ abstract_syntax_tree balloon_parse::block()
 {
 	abstract_syntax_tree new_node;
 	abstract_syntax_tree temp;
-	new_node.set_type(__block);
+	new_node.set_type(__normal_block);
 	get_token();
 	if(this_token.type!=__left_brace)
 	{
diff --git a/balloon/balloon_scope.h b/balloon/balloon_scope.h
index aeb09c9..22a5a2d 100644
--- a/balloon/balloon_scope.h
+++ b/balloon/balloon_scope.h
@@ -6,6 +6,14 @@ class balloon_scope
 	private:
 		std::list<var> global;
 		std::list<std::list<std::list<var> > > scope_list;
+		/*
+			example:
+				std::list<var> global                  // global scope
+				std::list<std::list<std::list<var> > > // total scope
+					-> std::list<std::list<var> >      // block scope
+						->std::list<var>               // local scope
+							-> var -> var -> var -> var
+		*/
 	public:
 		void set_clear()
 		{
diff --git a/balloon/balloon_type.h b/balloon/balloon_type.h
index ff282a9..c099ed3 100644
--- a/balloon/balloon_type.h
+++ b/balloon/balloon_type.h
@@ -51,7 +51,7 @@ enum parse_type
 	//basic elements
 	
 	__null_node,
-	__block,
+	__normal_block,
 	__array,
 	__hash,
 	__root,
@@ -65,6 +65,7 @@ enum parse_type
 	__call_hash,
 	__call_function
 };
+
 void print_detail_token(int type)
 {
 	std::string context="";
@@ -119,7 +120,7 @@ void print_detail_token(int type)
 		case __string:            context="str";break;
 		
 		case __null_node:         context="null node";break;
-		case __block:             context="block";break;
+		case __normal_block:      context="block";break;
 		case __array:             context="array";break;
 		case __hash:              context="hash";break;
 		case __root:              context="root";break;
@@ -138,6 +139,34 @@ void print_detail_token(int type)
 	return;
 }
 
+enum var_type
+{
+	__null_type,
+	__var_number,
+	__var_string,
+	__var_array,
+	__var_hash,
+	__var_function
+};
+
+void print_scalar(int type)
+{
+	std::string str="";
+	switch(type)
+	{
+		case __null_type:   str="null";break;
+		case __var_number:  str="number";break;
+		case __var_string:  str="string";break;
+		case __var_array:   str="array";break;
+		case __var_hash:    str="hash";break;
+		case __var_function:str="function";break;
+		default:            str="unknown";break;
+	}
+	std::cout<<str;
+	return;
+}
+
+
 enum runtime_error_type
 {
 	__process_exited_successfully,
diff --git a/balloon/balloon_var.h b/balloon/balloon_var.h
index 755ff2b..afb7f8e 100644
--- a/balloon/balloon_var.h
+++ b/balloon/balloon_var.h
@@ -1,33 +1,6 @@
 #ifndef __BALLOON_VAR_H__
 #define __BALLOON_VAR_H__
 
-enum var_type
-{
-	__null_type,
-	__var_number,
-	__var_string,
-	__var_array,
-	__var_hash,
-	__var_function
-};
-
-void print_scalar(int type)
-{
-	std::string str="";
-	switch(type)
-	{
-		case __null_type:   str="null";break;
-		case __var_number:  str="number";break;
-		case __var_string:  str="string";break;
-		case __var_array:   str="array";break;
-		case __var_hash:    str="hash";break;
-		case __var_function:str="function";break;
-		default:            str="unknown";break;
-	}
-	std::cout<<str;
-	return;
-}
-
 class var
 {
 	private:
diff --git a/balloon/main.cpp b/balloon/main.cpp
index b7f8314..c497aad 100644
--- a/balloon/main.cpp
+++ b/balloon/main.cpp
@@ -29,9 +29,9 @@ int main()
 		else if(command=="cls")
 		{
 			system("cls");
-			//windows system("cls");
-			//linux   system("clear");
-			//macOS   system("clear");
+			// Windows system("cls");
+			// Linux   system("clear");
+			// MacOS   system("clear");
 		}
 		else if(command=="rs")
 			prog.print_file();
@@ -59,7 +59,10 @@ int main()
 				pas.parse_main();
 			}
 			else
+			{
+				alert_sound();
 				std::cout<<">>[Lexer] error(s) found,stop."<<std::endl;
+			}	
 		}
 		else if(command=="ast")
 		{
@@ -72,10 +75,16 @@ int main()
 				if(!pas.get_error())
 					pas.print_generated_tree();
 				else
+				{
+					alert_sound();
 					std::cout<<">>[Parse] error(s) found,stop."<<std::endl;
+				}
 			}
 			else
+			{
+				alert_sound();
 				std::cout<<">>[Lexer] error(s) found,stop."<<std::endl;
+			}
 		}
 		else if(command=="run")
 		{
@@ -88,10 +97,16 @@ int main()
 				if(!pas.get_error())
 					pas.run_tree();
 				else
+				{
+					alert_sound();
 					std::cout<<">>[Parse] error(s) found,stop."<<std::endl;
+				}
 			}
 			else
+			{
+				alert_sound();
 				std::cout<<">>[Lexer] error(s) found,stop."<<std::endl;
+			}
 		}
 		else
 			prog.input_file(command);