Rob2233 发表于 2017-2-23 21:45, d. N; q! C4 Z$ ^8 i. h
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,( ^6 N0 B3 Z& @4 R+ E# m
这应该是比 ...
, f3 l8 _1 T! W: }; `: V" sthanks 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.