I haven't tried opium, but cannot imagine that Opium smells much like an opium den; and it is impossible to guess at what the millennium will smell like.
( ( ( ( ( I ( ( ( ( ( have n't ) ( tried opium ) ) , ) but ) ( ( can not ) ( imagine ( that ( Opium ( ( smells much ) ( like ( an ( opium den ) ) ) ) ) ) ) ) ) ) ; ) and ) ( it ( is ( impossible ( to ( guess ( at ( what ( ( the ( millennium ( will smell ) ) ) like ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (PRP I)) (VP (VP (VBP have) (RB n't) (VP (VBN tried) (NP (NN opium)))) (, ,) (CC but) (VP (MD can) (RB not) (VP (VB imagine) (SBAR (IN that) (S (NP (NNP Opium)) (VP (VBZ smells) (NP (RB much)) (PP (IN like) (NP (DT an) (NN opium) (NN den)))))))))) (: ;) (CC and) (S (NP (PRP it)) (VP (VBZ is) (ADJP (JJ impossible) (S (VP (TO to) (VP (VB guess) (PP (IN at) (SBAR (WHNP (WP what)) (S (NP (DT the) (JJ millennium) (NN will) (NN smell)) (VP (VBP like))))))))))) (. .)))
It's possible that Opium perfume smells like rabbits. 
( It ( ( ( 's possible ) ( that ( ( Opium perfume ) ( smells ( like rabbits ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ 's) (ADJP (JJ possible)) (SBAR (IN that) (S (NP (NNP Opium) (NN perfume)) (VP (VBZ smells) (PP (IN like) (NP (NNS rabbits))))))) (. .)))