Rob2233 发表于 2017-2-23 21:45( N7 R, t6 E+ i9 A) W3 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, ' b' w8 j: ?# l这应该是比 ...
# U9 d8 z! h6 v. |- 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.