( Pneumonia ( ( is ( ( a disease ) ( ( in which ) ( ( some ( of ( ( the alveoli ) ( of ( the lungs ) ) ) ) ) ( ( fill ( with fluid ) ) ( so ( ( gas exchange ) ( ( can not ) occur ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Pneumonia)) (VP (VBZ is) (NP (NP (DT a) (NN disease)) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (NP (DT some)) (PP (IN of) (NP (NP (DT the) (NNS alveoli)) (PP (IN of) (NP (DT the) (NNS lungs)))))) (VP (VBP fill) (PP (IN with) (NP (NN fluid))) (SBAR (IN so) (S (NP (NN gas) (NN exchange)) (VP (MD can) (RB not) (VP (VB occur)))))))))) (. .)))
Pneumonia is a disease in which some of the alveoli of the lungs fill with fluid so gas exchange   cannot occur.
(ROOT (S (NP (DT The) (NN term) (NN pneumonia)) (VP (VBZ is) (NP (NP (DT the) (NN name)) (PP (IN of) (NP (NP (DT the) (NN disease)) (SBAR (WHADVP (WRB where)) (S (NP (NP (DT some)) (PP (IN of) (NP (NP (DT the) (NNS alveoli)) (PP (IN of) (NP (DT the) (NNS lungs)))))) (VP (VBP fill) (PP (IN with) (NP (NN fluid))) (SBAR (IN so) (S (NP (PRP they)) (VP (MD can) (ADVP (RB no) (RB longer)) (VP (VB exchange) (NP (NN gas))))))))))))) (. .)))