diff --git a/bullet.py b/bullet.py
index 8c65fb7..f881020 100644
--- a/bullet.py
+++ b/bullet.py
@@ -22,22 +22,30 @@ class Bullet(Sprite):
         self.color = ai_settings.bullet_color
         self.speed_factor = ai_settings.bullet_speed_factor
 
-        def update(self):
-            """向上移动子弹"""
-            # 更新表示子弹位置的小数值
-            self.y -= self.speed_factor
-            # 更新表示子弹的rect的位置
-            self.rect.y = self.y
+    def update(self):
+        """向上移动子弹"""
+        # 更新表示子弹位置的小数值
+        self.y -= self.speed_factor
+        # 更新表示子弹的rect的位置
+        self.rect.y = self.y
 
-            def draw_bullet(self):
-                """在屏幕上绘制子弹"""
-                pygame.draw.rect(self.screen, self.color, self.rect)
+    def draw_bullet(self):
+        """在屏幕上绘制子弹"""
+        pygame.draw.rect(self.screen, self.color, self.rect)
 
 
-                class BossBullet(Sprite):
-                    """Boss发射的子弹"""
+class BossBullet(Sprite):
+    """Boss发射的子弹"""
 
-                    def __init__(self, ai_settings, screen, bossalien):
-                        """在飞船所处的位置创建一个子弹对象"""
-                        super(BossBullet, self).__init__()
-                        self.screen = screen
\ No newline at end of file
+    def __init__(self, ai_settings, screen, bossalien):
+        """在飞船所处的位置创建一个子弹对象"""
+        super(BossBullet, self).__init__()
+        self.screen = screen
+
+        # 在boss底部中央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.bossbullet_width,
+                                ai_settings.bossbullet_height)
+        self.rect.x = bossalien.x
+        self.rect.y = bossalien.rect.bottom
+        self.width = ai_settings.bossbullet_width
+        self.height = ai_settings.bossbullet_height
\ No newline at end of file