Él podría estar en el tren siguiente.


#1

I am pretty sure that próximo works just as well here instead of siguiente. See: https://www.duolingo.com/comment/2606940/Spanish-help-Siguiente-VS-próximo. But please correct me if I am wrong.


#2

I came here to post the same thing.

I want to use próximo but am not completely sure. I’ll ask my profesor and report back.


#3

Update: Apparently, siguiente is proper here because próximo would be used prior to the word tren.