The first trains used steam as the energy source, using wood or coal to burn as fuel.
(The first trains; used; steam; as the energy source) Context(The first trains used,List([0, 21))):(The first trains; used steam using; wood or coal; to burn as fuel)
The first trains used,List([0, 21))
The first trains The first trains
used used steam using
steam as the energy source
wood or coal to burn as fuel