diff --git a/ship.py b/ship.py
index 780d9ae..42ce1d7 100644
--- a/ship.py
+++ b/ship.py
@@ -18,4 +18,7 @@ class Ship(Sprite):
         # 将每艘新飞船放在屏幕底部中央
         self.rect.centerx = self.screen_rect.centerx
         self.rect.bottom = self.screen_rect.bottom
+
+        # 在飞船的属性center中存储小数值
+        self.center = float(self.rect.centerx)