( ( String frequency ) ( ( is ( controlled ( ( ( by ( ( adjusting tension ) ( for tuning ) ) ) and ) ( by ( ( manipulating length ) ( for performance ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP String) (NN frequency)) (VP (VBZ is) (VP (VBN controlled) (PP (PP (IN by) (S (VP (VBG adjusting) (NP (NN tension)) (PP (IN for) (NP (NN tuning)))))) (CC and) (PP (IN by) (S (VP (VBG manipulating) (NP (NN length)) (PP (IN for) (NP (NN performance))))))))) (. .)))
String frequency is controlled by adjusting tension for tuning and by manipulating length for performance.
(ROOT (S (NP (JJ Stringed) (NNS instruments)) (VP (MD can) (VP (VB help) (VP (VB show) (NP (NP (DT the) (NN relationship)) (PP (IN between) (NP (NN tension) (CC and) (NNS frequencies)))) (PP (IN in) (NP (NNS strings)))))) (. .)))