diff --git a/main.py b/main.py
index 39052fe..75571f0 100755
--- a/main.py
+++ b/main.py
@@ -7,10 +7,10 @@ from source.state import mainmenu, screen, level
 if __name__=='__main__':
     # 控制状态机运行
     game = tool.Control()
-    state_dict = {  c.MAIN_MENU: mainmenu.Menu(),
+    state_dict = {  c.MAIN_MENU:    mainmenu.Menu(),
                     c.GAME_VICTORY: screen.GameVictoryScreen(),
-                    c.GAME_LOSE: screen.GameLoseScreen(),
-                    c.LEVEL: level.Level()
+                    c.GAME_LOSE:    screen.GameLoseScreen(),
+                    c.LEVEL:        level.Level()
                     }
     game.setup_states(state_dict, c.MAIN_MENU)
     game.run()
diff --git a/source/constants.py b/source/constants.py
index bf5d3dc..8ab6161 100755
--- a/source/constants.py
+++ b/source/constants.py
@@ -639,4 +639,4 @@ CHOOSE = 'choose'
 PLAY = 'play'
 
 # 无穷大常量
-INF = float("inf")
+INF = float("inf")  # python传递字符串性能较低，故在这里对inf声明一次，以后仅需调用即可
diff --git a/source/state/screen.py b/source/state/screen.py
index c865f4d..a08793e 100644
--- a/source/state/screen.py
+++ b/source/state/screen.py
@@ -30,7 +30,7 @@ class Screen(tool.State):
         self.rect.y = 0
 
     def update(self, surface, current_time, mouse_pos, mouse_click):
-        if(current_time - self.start_time) < self.end_time:
+        if (current_time - self.start_time) < self.end_time:
             surface.fill(c.WHITE)
             surface.blit(self.image, self.rect)
         else: