The door opened and Severn stepped out.
( ( ( ( ( The door ) opened ) and ) ( Severn ( stepped out ) ) ) . )
(ROOT (S (S (NP (DT The) (NN door)) (VP (VBD opened))) (CC and) (S (NP (NNP Severn)) (VP (VBD stepped) (PRT (RP out)))) (. .)))
They approached as the door was opened.
( They ( ( approached ( as ( ( the door ) ( was opened ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD approached) (SBAR (IN as) (S (NP (DT the) (NN door)) (VP (VBD was) (VP (VBN opened)))))) (. .)))