( cementite ( , ( sometimes ( ( called ( ( ( ( ( iron carbide ) , ) ( ( a ( hard compound ) ) ( of ( ( iron and ) carbon ) ) ) ) and ) ( other ( carbide-forming elements ) ) ) ) ; ) ) ) )
(ROOT (S (ADVP (RB cementite)) (, ,) (ADVP (RB sometimes)) (VP (VBD called) (NP (NP (NN iron) (NN carbide)) (, ,) (NP (NP (DT a) (JJ hard) (NN compound)) (PP (IN of) (NP (NN iron) (CC and) (NN carbon)))) (CC and) (NP (JJ other) (JJ carbide-forming) (NNS elements)))) (: ;)))
cementite, sometimes called iron carbide, a hard compound of iron and carbon and other carbide-forming elements;
(ROOT (S (NP (NP (JJ Binary) (NNS compounds)) (PP (IN of) (NP (NP (NN carbon)) (PP (IN with) (NP (ADJP (RBR less) (JJ electronegative)) (NNS elements)))))) (VP (VBP are) (VP (VBN called) (NP (NNS carbides)))) (. .)))