At 9:03:11, United Airlines Flight 175 struck the South Tower of the World Trade Center.
( ( At 9:03:11 ) ( , ( ( United ( Airlines ( Flight 175 ) ) ) ( ( struck ( ( the ( South Tower ) ) ( of ( the ( World ( Trade Center ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (CD 9:03:11))) (, ,) (NP (NNP United) (NNP Airlines) (NNP Flight) (CD 175)) (VP (VBD struck) (NP (NP (DT the) (NNP South) (NNP Tower)) (PP (IN of) (NP (DT the) (NNP World) (NNP Trade) (NNP Center))))) (. .)))
The South Tower of the World Trade Center was struck at 9:03:11.
( ( ( The ( South Tower ) ) ( of ( the ( World ( Trade Center ) ) ) ) ) ( ( was ( struck ( at 9:03:11 ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NNP South) (NNP Tower)) (PP (IN of) (NP (DT the) (NNP World) (NNP Trade) (NNP Center)))) (VP (VBD was) (VP (VBN struck) (PP (IN at) (NP (CD 9:03:11))))) (. .)))