Rob2233 发表于 2017-2-23 21:455 g/ a3 o' t: _5 x$ v2 z: t
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,! W- `, e2 k" ?7 Q& D% ?) }5 ?
这应该是比 ...
2 I# W( k2 C3 [- T# `; m! s6 zthanks 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.