diff --git a/my_Tetris.py b/my_Tetris.py
index b4db71f..e42c273 100644
--- a/my_Tetris.py
+++ b/my_Tetris.py
@@ -49,20 +49,31 @@ shape=random.choice(shape_list)
 index=random.randint(0,len(shape)-1)
 current_shape = shape[index]
 color=random.choice(cube_colors)
+
+def check(center):
+    for cube in current_shape:
+        cube=(cube[0]+center[0],cube[1]+center[1])
+        if cube[0]<1 or cube[1]<1 or cube[0]>grid_num_height\
+                or cube[1]>grid_num_width:
+            return False
 while True:
     for event in pygame.event.get():
         if event.type == locals.QUIT:
             exit()
         if event.type == locals.KEYDOWN:
-            if event.key == locals.K_RIGHT:     # 向右
-                if center[1] < 15:
-                    center[1] += 1
+            if event.key == locals.K_LEFT:     # 向左
+                center[1]=center[1]-1
+                if center[1]==center[1]+1:
+                    if check(center)==False:
+                        center[1]=center[1]-1
             elif event.key == locals.K_LEFT:    # 向左
-                if center[1] > 1:
-                    center[1] -= 1
+                if center[1]==center[1]-1
+                     if check(center)==False:
+                            center[1]=center[1]+1                                    
             elif event.key == locals.K_DOWN:    # 向下
-                if center[0] < 25:
-                    center[0] += 1
+                if center[0]=center[0]+1 
+                    if check(center)==False:
+                    center[0]=center[0]-1 
 
     # 将背景图画上去
     screen.blit(background, (0, 0))