Rob2233 发表于 2017-2-23 21:45. E2 U; e" k9 K% a- B
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,. o! u3 @! b r6 ^9 Q
这应该是比 ...
- X: Q% _. g* n, W4 Q. H0 ]& 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.