Rob2233 发表于 2017-2-23 21:45$ P2 R [0 `1 T b" C+ Y' ]$ Z4 ?
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,8 Y/ f- V3 i" S: Y. D4 A/ u$ s5 L
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.