Rob2233 发表于 2017-2-23 21:45, \; D1 w7 T* A8 h; i
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, " W2 j3 ^5 t' V+ d0 f O$ U这应该是比 ...
2 A+ j0 P! n9 z; B7 Ethanks 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.