Rob2233 发表于 2017-2-23 21:452 k K- S( I& K% n
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, & y4 x% ?* T. \1 {这应该是比 ...
, l5 S1 x1 A1 \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.