But even without them, he would certainly have understood that the attacks on the World Trade Center would already have unfolded, given Flight 93's tardy departure from Newark.
( But ( ( even ( without them ) ) ( , ( he ( ( ( ( ( would certainly ) ( have ( understood ( that ( ( ( the attacks ) ( on ( the ( World ( Trade Center ) ) ) ) ) ( ( would already ) ( have unfolded ) ) ) ) ) ) ) , ) ( given ( ( ( Flight ( 93 's ) ) ( tardy departure ) ) ( from Newark ) ) ) ) . ) ) ) ) )
(ROOT (S (CC But) (PP (RB even) (IN without) (NP (PRP them))) (, ,) (NP (PRP he)) (VP (MD would) (ADVP (RB certainly)) (VP (VB have) (VP (VBN understood) (SBAR (IN that) (S (NP (NP (DT the) (NNS attacks)) (PP (IN on) (NP (DT the) (NNP World) (NNP Trade) (NNP Center)))) (VP (MD would) (ADVP (RB already)) (VP (VB have) (VP (VBD unfolded))))))))) (, ,) (PP (VBN given) (NP (NP (NP (NNP Flight) (CD 93) (POS 's)) (ADJP (JJ tardy)) (NN departure)) (PP (IN from) (NP (NNP Newark))))) (. .)))
He understood that Flight 93's late departure from Newark meant that the attacks would have already unfolded, even without them.
( He ( ( understood ( that ( ( ( ( Flight ( 93 's ) ) ( late departure ) ) ( from Newark ) ) ( meant ( that ( ( the attacks ) ( would ( have ( already ( ( ( unfolded , ) even ) ( without them ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD understood) (SBAR (IN that) (S (NP (NP (NP (NNP Flight) (CD 93) (POS 's)) (JJ late) (NN departure)) (PP (IN from) (NP (NNP Newark)))) (VP (VBD meant) (SBAR (IN that) (S (NP (DT the) (NNS attacks)) (VP (MD would) (VP (VB have) (VP (ADVP (RB already)) (VBZ unfolded) (, ,) (ADVP (RB even)) (PP (IN without) (NP (PRP them)))))))))))) (. .)))