20以内退位减法13-9= 15-8= 14-7= 14-8= 11-3= 11-6= 13-7= 13-4= 16-9= 18-9= 13-9= 12-3= 12-4= 12-8= 15-6= 14-8= 11-8= 14-5= 11-9= 11-4= 13-6= 11-7= 11-8= 15-7= 12-5= 16-8= 12-8= 12-5= 11-6= 11-5= 11-3= 12-3= 11-8= 17-8= 12-4= 12-9= 15-8= 14-9= 16-7= 12-8= 16-7= 15-7= 14-5= 14-7= 14-7= 12-8= 14-7= 14-8= 12-8= 17-8= 15-8= 11-4= 17-8= 11-3= 17-9= 13-7= 12-5= 15-8= 12-8= 18-9= 11-6= 12-5= 11-9= 16-8= 13-6= 16-9= 12-6= 13-9= 14-5= 14-6= 13-4= 16-7= 16-7= 13-4= 12-6= 11-7= 13-6= 16-8= 12-6= 11-9= 14-7= 12-6= 16-9= 14-9= 14-6= 11-9= 15-9= 11-8= 16-9= 13-6= 13-8= 18-9= 11-5= 12-9= 14-7= 15-6= 16-9= 17-9= 11-9= 12-9= 改错： 20以内退位减法12-3= 17-8= 14-6= 13-7= 14-9= 11-7= 18-9= 16-9= 11-5= 12-8= 13-8= 13-8= 12-8= 11-3= 11-6= 11-9= 14-9= 11-7= 11-5= 12-3= 11-8= 14-9= 18-9= 12-6= 16-7= 17-8= 13-4= 11-5= 13-7= 12-6= 12-8= 12-8= 14-5= 11-7= 13-5= 15-7= 18-9= 13-9= 14-8= 13-9= 11-5= 17-9= 11-5= 15-8= 15-9= 18-9= 13-8= 11-6= 11-3= 16-7= 16-8= 11-4= 13-6= 13-4= 13-6= 12-5= 14-8= 13-9= 12-5= 11-9= 11-2= 11-3= 14-9= 13-6= 16-7= 15-7= 15-8= 15-6= 17-8= 15-9= 11-2= 15-7= 12-3= 11-4= 14-6= 12-9= 12-6= 15-6= 12-9= 15-8= 11-9= 11-7= 15-6= 11-7= 14-9= 13-5= 14-6= 12-4= 13-5= 16-7= 15-9= 13-5= 16-7= 14-7= 11-5= 12-9= 13-5= 12-5= 11-7= 15-9= 改错： 20以内退位减法14-5= 12-5= 13-9= 11-6= 15-8= 15-9= 16-8= 13-9= 13-8= 15-8= 14-8= 12-8= 15-8= 16-7= 12-9= 15-8= 14-9= 16-9= 11-9= 17-9= 14-9= 16-8= 11-9= 11-9= 13-4= 12-3= 12-6= 17-9= 11-7= 12-5= 12-6= 11-5= 12-3= 11-5= 12-4= 15-9= 14-6= 14-9= 11-2= 16-8= 16-8= 14-9= 13-9= 13-9= 13-4= 12-4= 15-9= 13-4= 15-6= 13-8= 14-9= 11-3= 13-7= 12-3= 12-5= 13-4= 15-8= 13-5= 12-9= 11-7= 11-7= 14-5= 12-8= 16-8= 11-4= 13-7= 15-6= 11-8= 11-3= 12-5= 14-9= 14-6= 11-7= 12-8= 12-6= 13-7= 15-9= 11-8= 11-2= 16-8= 14-8= 15-9= 12-6= 13-8= 14-7= 14-6= 13-7= 16-7= 13-7= 16-8= 15-8= 14-9= 15-8= 13-8= 14-6= 12-5= 14-9= 11-7= 17-9= 16-7= 改错： 20以内退位减法14-6= 13-6= 15-7= 11-6= 13-7= 11-5= 12-7= 15-9= 14-9= 14-7= 17-9= 11-9= 15-7= 14-8= 13-5= 13-5= 11-7= 12-7= 13-9=