( ( The ( smallest ( Milky ( Way ( dwarf galaxies ) ) ) ) ) ( ( are ( ( ( only 500 ) light-years ) ( in diameter ) ) ) . ) )
(ROOT (S (NP (DT The) (JJS smallest) (JJ Milky) (NN Way) (NN dwarf) (NNS galaxies)) (VP (VBP are) (NP (NP (QP (RB only) (CD 500)) (NNS light-years)) (PP (IN in) (NP (NN diameter))))) (. .)))
The smallest Milky Way dwarf galaxies are only 500 light-years in diameter.
(ROOT (FRAG (S (S (VP (TO To) (VP (VB express) (NP (NP (DT the) (NN distance)) (PP (IN between) (NP (NP (DT the) (JJ milky) (NN way) (NN galaxy)) (CC and) (NP (JJ other) (NNS galaxies)))))))) (, ,) (NP (NP (DT the) (ADJP (RBS most) (JJ appropriate)) (NN unit)) (PP (IN of) (NP (NN measurement)))) (VP (VBZ is) (NP (DT the) (NN light-year))))))