( ( For example ) ( , ( calories ( ( is ( ( a measure ) ( of ( food energy ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (NN example))) (, ,) (NP (NNS calories)) (VP (VBZ is) (NP (NP (DT a) (NN measure)) (PP (IN of) (NP (NN food) (NN energy))))) (. .)))
For example, calories is a measure of food energy.
(ROOT (S (NP (NP (DT The) (NN energy) (NN content)) (PP (IN of) (NP (NNS foods)))) (VP (VBZ is) (ADVP (RB often)) (VP (VBN expressed) (PP (IN in) (NP (NNS calories))))) (. .)))
The energy content of foods is often expressed in calories.