"If you people only knew how fatally easy it is to poison some one by mistake, you wouldn't joke about it. 
( `` ( ( If ( ( you people ) ( only ( knew ( ( how ( fatally easy ) ) ( it ( ( is ( to poison ) ) ( ( some one ) ( by mistake ) ) ) ) ) ) ) ) ) ( , ( you ( ( ( would n't ) ( joke ( about it ) ) ) . ) ) ) ) )
(ROOT (S (`` ``) (SBAR (IN If) (S (NP (PRP you) (NNS people)) (ADVP (RB only)) (VP (VBD knew) (SBAR (WHADVP (WRB how) (ADJP (RB fatally) (JJ easy))) (S (NP (PRP it)) (VP (VBZ is) (PP (TO to) (NP (NN poison))) (NP (NP (DT some) (NN one)) (PP (IN by) (NP (NN mistake)))))))))) (, ,) (NP (PRP you)) (VP (MD would) (RB n't) (VP (VB joke) (PP (IN about) (NP (PRP it))))) (. .)))
Many people have poisoned someone by mistake.
( ( Many people ) ( ( have ( ( poisoned someone ) ( by mistake ) ) ) . ) )
(ROOT (S (NP (JJ Many) (NNS people)) (VP (VBP have) (NP (NP (VBN poisoned) (NN someone)) (PP (IN by) (NP (NN mistake))))) (. .)))