Rob2233 发表于 2017-2-23 21:45+ [# w" C q* ?' a" x
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, ( P- u& H7 S+ i. a6 w. o" s7 i/ F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.