( ( ( ( ( ( Most patients ) ( ( ( develop pneumonia ) , ) ( ( a condition ) ( ( in which ) ( ( some ( of ( ( the ( lungs ' ) ) ( air sacs ) ) ) ) ( fill ( with ( ( fluid or ) pus ) ) ) ) ) ) ) ) , ) so ) ( air ( is excluded ) ) ) . )
(ROOT (S (S (NP (JJS Most) (NNS patients)) (VP (VP (VBP develop) (NP (NN pneumonia))) (, ,) (NP (NP (DT a) (NN condition)) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (NP (DT some)) (PP (IN of) (NP (NP (DT the) (NNS lungs) (POS ')) (NN air) (NNS sacs)))) (VP (VBP fill) (PP (IN with) (NP (NN fluid) (CC or) (NN pus))))))))) (, ,) (IN so) (S (NP (NN air)) (VP (VBZ is) (VP (VBN excluded)))) (. .)))
Most patients develop pneumonia, a condition in which some of the lungs' air sacs fill with fluid or pus, so air is excluded.
(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))))))))))))) (. .)))