diff --git a/doc/demo01_hello/hello.md b/doc/demo01_hello/hello.md
index fb28ae7..24f1ee3 100644
--- a/doc/demo01_hello/hello.md
+++ b/doc/demo01_hello/hello.md
@@ -31,4 +31,14 @@ ue虽然开源源代码，但是代码量太大，历史包袱太重，不适合
 使用godot你既可以用GDScript去编写代码，也可以用C++去编写代码，还可以去改底层引擎代码
 ```
 
-- 用godot你能感觉我能把控底层，我能把控每一行代码的底层细节，这个是程序员的浪漫，godot在国外比较火是有原因的
\ No newline at end of file
+- 用godot你能感觉我能把控底层，我能把控每一行代码的底层细节，这个是程序员的浪漫，godot在国外比较火是有原因的
+
+# 为使用godot我应该选择什么语言，C# or GDScript
+
+- gds更加简单，支持的更加完整，而且是脚本可以热更新
+- C#很多库用不了，有限制，如果是为了性能可以在godot中使用C++
+- C#对于godot来说比较重，推荐gds
+- unity在很久之前也同时支持过js和C#，最后放弃了js，主要是因为unity是mono和C#非常友好
+- godot使用C++去解释执行gds，这个时候对于godot来说比较重，推荐gds
+- 通过学习gds也可以学到一些编译原理的知识
+- godot不仅仅是一个游戏引擎，而且还是一个优质的学习资源
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diff --git a/scene/demo_test/DemoTest.tscn b/scene/demo_test/DemoTest.tscn
new file mode 100644
index 0000000..f882b8a
--- /dev/null
+++ b/scene/demo_test/DemoTest.tscn
@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=2]
+
+[ext_resource path="res://script/demo_test/demoTest.gd" type="Script" id=1]
+
+[node name="Node2D" type="Node2D"]
+script = ExtResource( 1 )
diff --git a/script/demo_test/demoTest.gd b/script/demo_test/demoTest.gd
new file mode 100644
index 0000000..110a5cf
--- /dev/null
+++ b/script/demo_test/demoTest.gd
@@ -0,0 +1,23 @@
+extends Node2D
+
+const RandomUtils = preload("res://util/RandomUtils.gd")
+
+var count = 0
+
+func _ready():
+	print(RandomUtils.randomBoolean())
+	randomize()
+	
+	
+func _process(delta):
+	count = count + 1
+	if count % 100 == 0:
+		randomTest()
+	pass
+	
+
+func randomTest():
+	print(RandomUtils.randomBoolean())
+	print(RandomUtils.randomInt())
+	print(RandomUtils.randomIntLimit(2))
+	print(RandomUtils.randomIntRange(-2147483648, -2147483646))
diff --git a/util/NumberUtils.gd b/util/NumberUtils.gd
new file mode 100644
index 0000000..ef76bb4
--- /dev/null
+++ b/util/NumberUtils.gd
@@ -0,0 +1,6 @@
+extends Object
+
+const MIN_INT: int = -2147483648
+
+const MAX_INT: int = 2147483647
+
diff --git a/util/RandomUtils.gd b/util/RandomUtils.gd
index d1d0c67..612a828 100644
--- a/util/RandomUtils.gd
+++ b/util/RandomUtils.gd
@@ -1,8 +1,40 @@
 extends Object
 
+const NumberUtils = preload("res://util/NumberUtils.gd")
+const StringUtils = preload("res://util/StringUtils.gd")
 
-const random = [null, false]
+const random = [false, null]
 
-static func init():
-	random[0] = RandomNumberGenerator.new()
+# 单例模式
+static func getRandom() -> RandomNumberGenerator:
+	if random[0]:
+		return random[1]
+	var randomGenerator = RandomNumberGenerator.new()
+	randomGenerator.randomize()
+	random[1] = randomGenerator
+	return randomGenerator
+
+
+static func randomBoolean() -> bool:
+	return 1 == getRandom().randi_range(0, 2)
+
+
+# 获得随机数[-2^32, 2^32)
+static func randomInt() -> int:
+	return randomIntRange(NumberUtils.MIN_INT, NumberUtils.MAX_INT)
+
+# 获得指定范围内的随机数 [0,limit)
+static func randomIntLimit(limit: int) -> int:
+	return randomIntRange(0, limit)
+
+# 获得随机数[-2^32, 2^32)
+static func randomIntRange(from: int, to: int) -> int:
+	if from < NumberUtils.MIN_INT:
+		push_error(StringUtils.format("from [{}] shoud be >= [{}]", [from, NumberUtils.MIN_INT]))
+		return 0
 	
+	if to > NumberUtils.MAX_INT:
+		push_error(StringUtils.format("to [{}] should be <= [{}]", [from, NumberUtils.MAX_INT]))
+		return 0
+	
+	return getRandom().randi_range(from, to - 1)