Rob2233 发表于 2017-2-23 21:452 B& ?: n5 v U
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,: `) Q8 d- T- B1 h l
这应该是比 ...
) E; s" ]+ O" h5 R; D
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.