Rob2233 发表于 2017-2-23 21:451 J/ P& U! A: Z* `0 k4 Z
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,. M) }! n5 Z$ S2 \0 f+ Q5 o
这应该是比 ...
# U0 ?4 ~* w. C. B/ X9 Othanks 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.