( ( ( ( ( This ( ( is only ) ( a prediction ) ) ) , ) and ) ( ( the timing ) ( may ( be ( off ( by ( several hours ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT This)) (VP (VBZ is) (ADVP (RB only)) (NP (DT a) (NN prediction)))) (, ,) (CC and) (S (NP (DT the) (NN timing)) (VP (MD may) (VP (VB be) (ADJP (IN off) (PP (IN by) (NP (JJ several) (NNS hours))))))) (. .)))
This is only a prediction, and the timing may be off by several hours.
(ROOT (S (NP (NNS Bacteria)) (VP (MD may) (VP (VB divide) (NP (NP (QP (JJ several) (NNS times))) (NP (DT an) (NN hour))))) (. .)))