They knew American 77 was lost.
( They ( ( knew ( ( American 77 ) ( was lost ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD knew) (SBAR (S (NP (NNP American) (CD 77)) (VP (VBD was) (VP (VBN lost)))))) (. .)))
They knew other airplanes were lost too.
( They ( ( knew ( ( other airplanes ) ( were ( lost too ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD knew) (SBAR (S (NP (JJ other) (NNS airplanes)) (VP (VBD were) (VP (VBN lost) (ADVP (RB too))))))) (. .)))