( ( At ( absolute zero ) ) ( , ( ( ( ( a ( hypothetical temperature ) ) , ) ( all ( molecular movement ) ) ) ( stops . ) ) ) )
(ROOT (S (PP (IN At) (NP (JJ absolute) (CD zero))) (, ,) (NP (NP (DT a) (JJ hypothetical) (NN temperature)) (, ,) (NP (DT all) (JJ molecular) (NN movement))) (VP (VBZ stops)) (. .)))
At absolute zero, a hypothetical temperature, all molecular movement stops.
(ROOT (S (NP (NP (DT The) (NN temperature)) (SBAR (WHPP (IN at) (WHNP (WDT which))) (S (NP (DT all) (JJ molecular) (NN motion)) (VP (VBZ has) (VP (VBN ceased)))))) (VP (VBZ is) (VP (VBN called) (NP (JJ absolute) (NN zero)))) (. .)))