 Hold on a second.
( ( Hold ( on ( a second ) ) ) . )
(ROOT (S (VP (VB Hold) (PP (IN on) (NP (DT a) (NN second)))) (. .)))
Hold on for a few minutes.
( ( ( Hold on ) ( for ( a ( few minutes ) ) ) ) . )
(ROOT (S (VP (VB Hold) (PRT (RP on)) (PP (IN for) (NP (DT a) (JJ few) (NNS minutes)))) (. .)))