diff --git a/bullet.py b/bullet.py
index 195965d..8c65fb7 100644
--- a/bullet.py
+++ b/bullet.py
@@ -31,4 +31,13 @@ class Bullet(Sprite):
 
             def draw_bullet(self):
                 """在屏幕上绘制子弹"""
-                pygame.draw.rect(self.screen, self.color, self.rect)
\ No newline at end of file
+                pygame.draw.rect(self.screen, self.color, self.rect)
+
+
+                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