Rob2233 发表于 2017-2-23 21:457 b0 V* ^( ^& _1 U: }( N, N3 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, , t2 W$ O0 ?6 R这应该是比 ...
_$ T1 ^ @% P& e8 m) H3 @
thanks 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.