diff --git a/alien.py b/alien.py
deleted file mode 100644
index d74e403..0000000
--- a/alien.py
+++ /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_settings, screen):
-        """初始化外星人并设置其初始位置"""
-        super().__init__()
-        self.screen = screen
-        self.ai_settings = ai_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()
-
-        # 每个外星人初始都在屏幕左上角，设置为其宽高以进行留白
-        self.rect.x = self.rect.width
-        self.rect.y = self.rect.height * 2
-
-        self.x = float(self.rect.x)
-
-
-    def update(self):
-        """向左或向右右移动外星人"""
-        self.x += self.ai_settings.alien_speed_factor * self.ai_settings.fleet_direction
-        self.rect.x = self.x
-
-
-    def check_edges(self):
-        screen_rect = self.screen.get_rect()
-        if self.rect.right >= screen_rect.right:
-            return True
-        elif self.rect.left <= screen_rect.left:
-            return True