acquainted with the author 's work , on the other hand , 
(ROOT (S (S (VP (VBN acquainted) (PP (IN with) (NP (NP (DT the) (NN author) (POS 's)) (NN work))))) (, ,) (PP (IN on) (NP (DT the) (JJ other) (NN hand))) (, ,)))
(ROOT (S (S (VP (VBN ) (PP (IN ) (NP (NP (DT ) (NN ) (POS )) (NN ))))) (, ) (PP (IN ) (NP (DT ) (JJ ) (NN ))) (, )))