I mustn't keep you.
( I ( ( ( must n't ) ( keep you ) ) . ) )
(ROOT (S (NP (PRP I)) (VP (MD must) (RB n't) (VP (VB keep) (NP (PRP you)))) (. .)))
I can keep you without any consequences.
( I ( ( can ( ( keep you ) ( without ( any consequences ) ) ) ) . ) )
(ROOT (S (NP (PRP I)) (VP (MD can) (VP (VB keep) (NP (PRP you)) (PP (IN without) (NP (DT any) (NNS consequences))))) (. .)))