( They ( ( form ( at ( temperatures ( as ( ( ( ( ( ( ( ( ( ( high ( as ( ( ( 1,000 ( o Celsius ) ) ( -LRB- ( C -RRB- ) ) ) ( -LRB- ( ( ( Hunsinger , ) 1997 ) -RRB- ) ) ) ) ) and ) ( as ( low ( as ( ( 20 ( o C ) ) ( in ( the gas ) ) ) ) ) ) ) , ) liquid ) , ) or ) ( even solid ) ) phase ) ( -LRB- ( ( ( Klimm , ) 1998 ) -RRB- ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP form) (PP (IN at) (NP (NP (NNS temperatures)) (PP (IN as) (NP (NP (ADJP (ADJP (JJ high) (PP (IN as) (NP (NP (NP (CD 1,000) (NN o) (NNS Celsius)) (PRN (-LRB- -LRB-) (NP (NNP C)) (-RRB- -RRB-))) (PRN (-LRB- -LRB-) (NP (NNP Hunsinger)) (, ,) (NP (CD 1997)) (-RRB- -RRB-))))) (CC and) (ADJP (RB as) (JJ low) (PP (IN as) (NP (NP (CD 20) (NN o) (NNP C)) (PP (IN in) (NP (DT the) (NN gas)))))) (, ,) (ADJP (JJ liquid)) (, ,) (CC or) (ADJP (RB even) (JJ solid))) (NN phase)) (PRN (-LRB- -LRB-) (NP (NNP Klimm)) (, ,) (NP (CD 1998)) (-RRB- -RRB-))))))) (. .)))
They form at temperatures as high as 1,000 o Celsius (C) (Hunsinger, 1997) and as low as 20 o C in the gas, liquid, or even solid phase (Klimm, 1998).
(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.