diff --git a/bullet.py b/bullet.py
index 4f76017..06e8fcf 100644
--- a/bullet.py
+++ b/bullet.py
@@ -1,11 +1,23 @@
-import pygame
-from pygame.sprite import Sprite
-
-
-class Bullet(Sprite):
-    """一个对飞船发射的子弹进行管理的类"""
-
-    def __init__(self, ai_settings, screen, ship):
-        """在飞船所处的位置创建一个子弹对象"""
-        super(Bullet, self).__init__()
-        self.screen = screen
\ No newline at end of file
+import pygame
+from pygame.sprite import Sprite
+
+
+class Bullet(Sprite):
+    """一个对飞船发射的子弹进行管理的类"""
+
+    def __init__(self, ai_settings, screen, ship):
+        """在飞船所处的位置创建一个子弹对象"""
+        super(Bullet, self).__init__()
+        self.screen = screen
+
+        # 在(0,0)处创建一个表示子弹的矩形，再设置正确的位置
+        self.rect = pygame.Rect(0, 0, ai_settings.bullet_width,
+                                ai_settings.bullet_height)
+        self.rect.centerx = ship.rect.centerx
+        self.rect.top = ship.rect.top
+
+        # 存储用小数表示的子弹位置
+        self.y = float(self.rect.y)
+
+        self.color = ai_settings.bullet_color
+        self.speed_factor = ai_settings.bullet_speed_factor