输入如下程序

>choice=c('choice1','choice2','choice3')

>sex=c('f','m','f')

> income=c(30,40,50)

>time1=c(23,46,57)

> time2=c(34,44,34)

> time3=c(45,64,56)

> cost1=c(45,35,56)

> cost2=c(40,64,46)

> cost3=c(30,31,75)

> comfort1=c(34,34,46)

> comfort2=c(44,13,43)

> comfort3=c(56,35,64)

> moss=data.frame(choice=choice,sex=sex,income=income,time1=time1,time2=time2,

time3=time3,cost1=cost1,cost2=cost2,cost3=cost3,comfort1=comfort1,comfort2=comfort2,comfort3=comfort3)

接下来使用mlogit.data函数，把moss改为long表示形式，出现如下蓝色字体的错误提示，请高手解答一下，不甚感激！

moslong=mlogit.data(moss,choice='choice',varying=4:12,shape='wide',alt.levels=1:3)

错误于guess(varying):

  failed to guess time-varying variables fromtheir names