Rob2233 发表于 2017-2-23 21:45+ I, x7 s2 H: R2 g
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, 5 H/ c4 }+ z5 t2 f/ d. P6 t, Z/ D这应该是比 ...
( J- L7 O" c% |! W2 Q' rthanks 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.