题干
写出差是9的减法算式，你能写出多少道?
( )－( )=9 ( )－( )=9 ( )－( )=9 ( )－( )=9
( )－( )=9 ( )－( )=9 ( )－( )=9 ( )－( )=9
( )－( )=9 ( )－( )=9 ( )－( )=9 ( )－( )=9
答案(点此获取答案解析）
9-0=9, 10-1=9, 11-2=9, 12-3=9,13-4=9, 14-5=9, 15-6=9, 16-7=9,17-8=9, 18-9=9, 19-10=9, 20-11=9
