Rob2233 发表于 2017-2-23 21:45( d w, E0 U2 f! w) R5 S4 E& {) q: ]
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, % |% T5 P! G- f这应该是比 ...
0 Y% d/ S3 M5 N# o" kthanks 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.