so easily after a few tries and become expert fighters after a few weeks 
(ROOT (S (ADVP (RB so) (RB easily)) (PP (IN after) (NP (DT a) (JJ few) (NNS tries))) (CC and) (VP (VB become) (NP (NN expert) (NNS fighters)) (PP (IN after) (NP (DT a) (JJ few) (NNS weeks))))))
(ROOT (S (ADVP (RB ) (RB )) (PP (IN ) (NP (DT ) (JJ ) (NNS ))) (CC ) (VP (VB ) (NP (NN ) (NNS )) (PP (IN ) (NP (DT ) (JJ ) (NNS ))))))