Answer:
Fuel is burned outside the engine
Step-by-step explanation:
A steam engine is a heat engine that uses steam as a working fluid, the steam engine performs due to the pressure produced by the steam. the fuel which is the steam is been applied/burned outside the engine but it is the pressure of the steam(fuel) that drives the steam engine into action.
All heat is used up for work some heat generated is lost to the surroundings it is only in ideal situation that all heat produced is used up for work. the type of engine that has its fuel burnt inside is a combustible engine as seen in modern day car Engine.
example of a steam Engine is A boiler full of water