people who have never picked a lock do so easily after a few tries and become expert fighters after a few weeks 
(ROOT (S (NP (NP (NNS people)) (SBAR (WHNP (WP who)) (S (VP (VBP have) (ADVP (RB never)) (VP (VBN picked) (NP (DT a) (NN lock))))))) (VP (VP (VB do) (ADVP (RB so)) (ADVP (RB easily)) (PP (IN after) (NP (DT a) (JJ few) (NNS tries)))) (CC and) (VP (VBP become) (NP (NN expert) (NNS fighters)) (PP (IN after) (NP (DT a) (JJ few) (NNS weeks)))))))
(ROOT (S (NP (NP (NNS )) (SBAR (WHNP (WP )) (S (VP (VBP ) (ADVP (RB )) (VP (VBN ) (NP (DT ) (NN ))))))) (VP (VP (VB ) (ADVP (RB )) (ADVP (RB )) (PP (IN ) (NP (DT ) (JJ ) (NNS )))) (CC ) (VP (VBP ) (NP (NN ) (NNS )) (PP (IN ) (NP (DT ) (JJ ) (NNS )))))))