( ( The ( boiling point ) ) ( ( is ( ( the temperature ) ( when ( ( a liquid ) ( becomes ( a gas ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ boiling) (NN point)) (VP (VBZ is) (NP (NP (DT the) (NN temperature)) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN liquid)) (VP (VBZ becomes) (NP (DT a) (NN gas))))))) (. .)))
The boiling point is the temperature when a liquid becomes a gas.
(ROOT (S (NP (NNS Gases) (CC and) (NNS liquids)) (VP (VBP become) (NP (NNS solids)) (PP (IN at) (NP (JJ low) (NNS temperatures)))) (. .)))
Gases and liquids become solids at low temperatures.