交換律:a+b+c=a+c+b;a×☆×☆=☆...
5+7 = 7+5 稱為交換律5+7+8 =(5+7)+8 ...
(5+7)+8=5+(7+8)是 (A)交換律 (B)分配律 (C)結合律 (..-阿摩線上測驗