( ( When ( ( certain ( brain cells ) ) ( ( are not ) ( able ( to ( function ( due ( to stroke ) ) ) ) ) ) ) ) ( , ( ( ( the parts ) ( of ( ( the body ) ( controlled ( by ( those ( brain cells ) ) ) ) ) ) ) ( ( are ( unable ( to function ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (JJ certain) (NN brain) (NNS cells)) (VP (VBP are) (RB not) (ADJP (JJ able) (S (VP (TO to) (VP (VB function) (ADJP (JJ due) (PP (TO to) (NP (NN stroke))))))))))) (, ,) (NP (NP (DT the) (NNS parts)) (PP (IN of) (NP (NP (DT the) (NN body)) (VP (VBN controlled) (PP (IN by) (NP (DT those) (NN brain) (NNS cells))))))) (VP (VBP are) (ADJP (JJ unable) (S (VP (TO to) (VP (VB function)))))) (. .)))
When certain brain cells are not able to function due to stroke, the parts of the body controlled by those brain cells are unable to function.
(ROOT (S (ADVP (RB Not) (RB surprisingly)) (, ,) (NP (JJ controlling) (NN flight)) (VP (VBZ is) (NP (NP (DT the) (NN function)) (PP (IN of) (NP (NP (DT the) (ADJP (RBS most) (JJ developed)) (NN part)) (PP (IN of) (NP (NP (DT a) (NN bird) (POS 's)) (NN brain))))))) (. .)))