( ( ( ETHER Denotes ) ( ( an ( organic compound ) ) ( characterized ( by ( ( the presence ) ( of ( an ( oxygen atom ) ) ) ) ) ) ) ) ( ( ( ( ( bonded directly ) ( to ( two ( carbon atoms ) ) ) ) , ) ( where ( ( the ( carbon atoms ) ) ( ( may not ) ( be ( ( double bonded ) ( to ( ( ( ( ( ( chalcogen -LRB- ) ( i.e. ( , ( oxygen ( , ( sulfur ( , ( selenium ( , ( or tellurium ) ) ) ) ) ) ) ) ) ) -RRB- ) , ) or ) ( ( triple bonded ) ( to nitrogen ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP ETHER) (NNP Denotes)) (SBAR (S (NP (DT an) (JJ organic) (NN compound)) (VP (VBD characterized) (PP (IN by) (NP (NP (DT the) (NN presence)) (PP (IN of) (NP (DT an) (NN oxygen) (NN atom))))))))) (VP (VBD bonded) (ADVP (RB directly)) (PP (TO to) (NP (CD two) (NN carbon) (NNS atoms))) (, ,) (SBAR (WHADVP (WRB where)) (S (NP (DT the) (NN carbon) (NNS atoms)) (VP (MD may) (RB not) (VP (VB be) (NP (NP (QP (RB double) (CD bonded))) (PP (TO to) (NP (NP (NP (NN chalcogen)) (-LRB- -LRB-) (NP (CD i.e.) (, ,) (NN oxygen) (, ,) (NN sulfur) (, ,) (NN selenium) (, ,) (CC or) (NN tellurium)) (-RRB- -RRB-)) (, ,) (CC or) (NP (NP (QP (RB triple) (CD bonded))) (PP (TO to) (NP (NN nitrogen)))))))))))) (. .)))
ETHER Denotes an organic compound characterized by the presence of an oxygen atom bonded directly to two carbon atoms, where the carbon atoms may not be double bonded to chalcogen (i.e., oxygen, sulfur, selenium, or tellurium), or triple bonded to nitrogen.
(ROOT (S (NP (NNS Ethers)) (VP (VBP are) (VP (VBN composed) (PP (IN of) (NP (NP (DT an) (NN oxygen) (NN atom)) (SBAR (WHNP (WDT that)) (S (VP (VBZ forms) (NP (JJ single) (NNS bonds)) (PP (IN with) (NP (CD two) (NN carbon) (NNS atoms)))))))))) (. .)))