回複：謝謝Jinjing， 但

來源: 於 2010-03-31 16:58:03 [舊帖] [給我悄悄話] 本文已被閱讀：次

I think only use examples: 5-3=2,7-3=4,11-7=4,...,2m+1-(2n+1)=2(m+n)...It is not easy to teach,good lucky.