Rob2233 发表于 2017-2-23 21:456 S; V# Q% G8 K2 V% _2 i/ J! j' U
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,+ G. i, W9 E" A" T' B8 A$ w
这应该是比 ...
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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.