In a single acting steam engine_. athe steam is admitted on one side of the piston and one working stroke is produced during each revolution of the crankshaft bthe steam is admitted, in turn, on both sides of the piston and one working stroke is produced during each revolution of the crankshaft cthe steam is admitted on one side of the piston and two working strokes are produced during each revolution of the crankshaft dthe steam is admitted, in turn, on both sides of the piston and two working strokes are produced during each revolution of the crankshaft