我一直在关注Ruby-on-Railstutorial中的练习由M.Hartl着。我已经完成了第4章中的所有练习,但仍停留在这一章上:Createthreehashescalledperson1,person2,andperson3,withfirstandlastnamesunderthekeys:firstand:last.Thencreateaparamshashsothatparams[:father]isperson1,params[:mother]isperson2,andparams[:child]isperson3.Verifythat,forexample,param