Rob2233 发表于 2017-2-23 21:450 p% h9 y2 w v' g
如果觉得难度不够的话,可以试试加拿大公开赛(Canadian Open Mathematics Challenge)的题, $ v- I1 N" [5 h6 h/ R这应该是比 ...
5 g& ^$ ?' U+ x) l6 r! i9 vthanks a lot as parents, but i guess my daughter going to hate you. i won't let her know who you are. please keep sending this kind good resource for all parents.