Rob2233 发表于 2017-2-23 21:45 - z& f x8 A; m) z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,. }7 v6 A6 b4 d/ |; w3 S
这应该是比 ...
) t$ U3 m8 [+ E, d7 w. K6 nthanks 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.