Rob2233 发表于 2017-2-23 21:45! L+ y1 l" C9 _/ B
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,2 M9 w$ I: ?1 |1 b4 c
这应该是比 ...
+ W( n4 s# r( ythanks 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.