( There ( ( are ( ( many ( possible sources ) ) ( of ( error ( in ( this experiment ) ) ) ) ) ) . ) )
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (JJ many) (JJ possible) (NNS sources)) (PP (IN of) (NP (NP (NN error)) (PP (IN in) (NP (DT this) (NN experiment))))))) (. .)))
There are many possible sources of error in this experiment.
(ROOT (S (NP (PRP You)) (ADVP (NP (NP (NN decrease) (NNS errors)) (PP (IN in) (NP (DT an) (NN experiment)))) (IN by)) (VP (VBP take) (NP (JJ many) (NNS measurements))) (. .)))