( ( Since ( ( hydrogen sulfide ) ( is ( ( a gas ) ( at ( room temperature ) ) ) ) ) ) ( , ( ingestion ( ( is ( unlikely ( to occur ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Since) (S (NP (NN hydrogen) (NN sulfide)) (VP (VBZ is) (NP (NP (DT a) (NN gas)) (PP (IN at) (NP (NN room) (NN temperature))))))) (, ,) (NP (NN ingestion)) (VP (VBZ is) (ADJP (JJ unlikely) (S (VP (TO to) (VP (VB occur)))))) (. .)))
Since hydrogen sulfide is a gas at room temperature, ingestion is unlikely to occur.
(ROOT (S (NP (NNP Hydrogen)) (VP (VBZ is) (PP (IN in) (NP (NP (NN gas) (NN form)) (PP (IN at) (NP (NN room) (NN temperature)))))) (. .)))