Rob2233 发表于 2017-2-23 21:45 # a, U6 o7 U O8 l. [8 T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,' \. u' X4 n3 I7 n4 h
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% X8 e e/ h. qthanks 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.