20以内的退位减法（2023-08-03）

20以内的退位减法（2023-08-03）：11-3= 14-9= 13-8= 18-9= 12-6= 15-8= 14-6= 12-7= 17-9= 12-4= 11-9= 13-8= 12-6= 15-8= 14-7= 11-6= 15-8= 12-6= 15-8= 13-9= 14-7= 15-8= 12-6= 15-8= 13-9= 14-7= 15-8= 12-6= 14-7= 13-8= 12-4= 11-9= 13-8= 12-4= 11-9= 14-7= 12-4= 11-9= 14-7= 13-8= 14-5= 16-8= 11-9= 14-7= 12-3= 15-6= 12-8= 13-6= 16-7= 17-8= 13-6= 14-5= 13-8= 11-9= 14-7= 11-3= 14-5= 13-8= 11-6= 14-7= 17-8= 11-9= 12-5= 13...