Rob2233 发表于 2017-2-23 21:45 q9 B: A/ j, o* K' l
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, . e0 g* R: }2 c8 x0 Q/ i$ n* w这应该是比 ...
+ Q1 ^9 q4 ?9 |6 x# X! 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.