those little kids don't understand it
( ( those ( little kids ) ) ( ( do n't ) ( understand it ) ) )
(ROOT (S (NP (DT those) (JJ little) (NNS kids)) (VP (VBP do) (RB n't) (VP (VB understand) (NP (PRP it))))))
The little kid understand it perfectly. 
( ( The ( little kid ) ) ( ( ( understand it ) perfectly ) . ) )
(ROOT (S (NP (DT The) (JJ little) (NN kid)) (VP (VBP understand) (NP (PRP it)) (ADVP (RB perfectly))) (. .)))