Rob2233 发表于 2017-2-23 21:45 + K7 \8 N' ]7 `6 W/ 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,* `4 J" i, ?* S/ M
这应该是比 ...
" C, R) B) `+ ^8 U+ j! X8 Z/ 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.