Rob2233 发表于 2017-2-23 21:458 u" E4 ]( Y8 w M/ u# a, R
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, $ a2 W! x$ r+ m这应该是比 ...
4 a. t- K7 d- P% i6 h4 K6 ^: G/ `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.