To our knowledge none of them had ever flown an actual airliner before.
( ( To ( our knowledge ) ) ( ( none ( of them ) ) ( ( ( had ever ) ( ( flown ( an ( actual airliner ) ) ) before ) ) . ) ) )
(ROOT (S (PP (TO To) (NP (PRP$ our) (NN knowledge))) (NP (NP (NN none)) (PP (IN of) (NP (PRP them)))) (VP (VBD had) (ADVP (RB ever)) (VP (VBN flown) (NP (DT an) (JJ actual) (NN airliner)) (ADVP (RB before)))) (. .)))
None of them had flown planes before but they had studied on the computer.
( ( None ( of them ) ) ( ( had ( ( flown planes ) ( before ( but ( they ( had ( studied ( on ( the computer ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NN None)) (PP (IN of) (NP (PRP them)))) (VP (VBD had) (VP (VBN flown) (NP (NNS planes)) (PP (IN before) (SBAR (CC but) (S (NP (PRP they)) (VP (VBD had) (VP (VBN studied) (PP (IN on) (NP (DT the) (NN computer)))))))))) (. .)))