He could make quite an issue out of the need to determine the characteristic impedance of their sky.
( He ( ( could ( ( ( make ( quite ( an issue ) ) ) out ) ( of ( the ( need ( to ( determine ( ( the ( characteristic impedance ) ) ( of ( their sky ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (MD could) (VP (VB make) (NP (PDT quite) (DT an) (NN issue)) (PRT (RP out)) (PP (IN of) (NP (DT the) (NN need) (S (VP (TO to) (VP (VB determine) (NP (NP (DT the) (JJ characteristic) (NN impedance)) (PP (IN of) (NP (PRP$ their) (NN sky))))))))))) (. .)))
He could have made an issue, but did not
( He ( ( ( ( could ( have ( made ( an issue ) ) ) ) , ) but ) ( did not ) ) )
(ROOT (S (NP (PRP He)) (VP (VP (MD could) (VP (VB have) (VP (VBN made) (NP (DT an) (NN issue))))) (, ,) (CC but) (VP (VBD did) (RB not)))))