Rob2233 发表于 2017-2-23 21:45: x5 G! B! ^& a. `* f: x
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, ) o% D3 M* \2 ]' v# Q1 \这应该是比 ...
; k' L! s0 P; uthanks 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.