But there's plenty more.
( But ( there ( ( ( 's plenty ) more ) . ) ) )
(ROOT (S (CC But) (NP (EX there)) (VP (VBZ 's) (ADVP (RB plenty)) (ADJP (JJR more))) (. .)))
There is not a sufficient amount. 
( There ( ( ( is not ) ( a ( sufficient amount ) ) ) . ) )
(ROOT (S (NP (EX There)) (VP (VBZ is) (RB not) (NP (DT a) (JJ sufficient) (NN amount))) (. .)))