diff --git a/bullet.py b/bullet.py
index 712cdd5..70d6abe 100644
--- a/bullet.py
+++ b/bullet.py
@@ -54,4 +54,33 @@ class Bullet(object):
         # 获得子弹矩形(x, y, width, height)
         self.rect = self.image.get_rect()
 
-    
\ No newline at end of file
+    # 设置子弹位置
+    def set_pos(self, x, y):
+        self.rect[0] = x
+        self.rect[1] = y
+
+    # 设置子弹速度
+    def set_speed(self, speed):
+        if self.is_enemy:
+            self.speed = speed
+        else:
+            self.speed = -speed
+
+    # 子弹移动
+
+    def action(self):
+        if not self.visible:
+            return
+        # 假设飞机矩形为plane_rect(10, 20, 200, 300)
+        # plane_rect.move_ip(10, 20), 那么结果是plane_rect(20, 40, 200, 300)
+        # 也就是原矩形x和y坐标加上move_ip函数x和y坐标，就是当前矩形新位置
+        self.rect.move_ip(0, self.speed)
+        # 如果子弹超出场景范围,则设置为不可见
+        if self.rect[1] < 0 or self.rect[1] > self.main_scene.size[1]:
+            self.visible = False
+
+    # 绘制子弹
+    def draw(self):
+        if not self.visible:
+            return
+        self.main_scene.scene.blit(self.image, (self.rect[0], self.rect[1]))