( It ( ( displays ( ( ( a ( four-headed arrow ) ) ( indicating ( any ( of ( the ( arrow keys ) ) ) ) ) ) ( will ( size ( the window ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ displays) (SBAR (S (NP (NP (DT a) (JJ four-headed) (NN arrow)) (VP (VBG indicating) (NP (NP (DT any)) (PP (IN of) (NP (DT the) (NN arrow) (NNS keys)))))) (VP (MD will) (VP (VBP size) (NP (DT the) (NN window))))))) (. .)))
It displays a four-headed arrow indicating any of the arrow keys will size the window.
(ROOT (S (NP (JJ Reversible) (NNS reactions)) (VP (VBP are) (VP (VBN indicated) (PP (IN by) (NP (NP (JJ opposite-headed) (NNS kinds)) (PP (IN of) (NP (NNS arrows))))))) (. .)))
Reversible reactions are indicated by opposite-headed kinds of arrows.