diff --git a/alien b/alien
deleted file mode 100644
index c4ba3ec..0000000
--- a/alien
+++ /dev/null
@@ -1,35 +0,0 @@
-import pygame
-from pygame.sprite import Sprite
-
-class Alien(Sprite):
-    """表示单个外星人的类"""
-
-    def __init__(self,ai_game):
-        """初始化外星人并设置其起始位置"""
-        super().__init__()
-        self.screen = ai_game.screen
-        self.settings = ai_game.settings
-
-        # 加载外星人图像并设置其rect属性
-        self.image = pygame.image.load('images/alien.bmp')
-        self.rect = self.image.get_rect()
-
-        # 每个外星人最初都在屏幕左上角附近
-        self.rect.x = self.rect.width
-        self.rect.y = self.rect.height
-
-        # 存储外星人的精确水平位置
-        self.x = float(self.rect.x)
-
-    def check_edges(self):
-        """如果外星人位于屏幕边缘，就返回True"""
-        screen_rect = self.screen.get_rect()
-        if self.rect.right >= screen_rect.right or self.rect.left <= 0:
-            return True
-
-    def update(self):
-        """向左或向右移动外星人"""
-        self.x += (self.settings.alien_speed *
-                   self.settings.fleet_direction)
-        self.rect.x = self.x
-        
\ No newline at end of file