The levadas were largely built by slave laborers from Africa, whose primary employment was on sugar plantations.
( ( The levadas ) ( ( ( were largely ) ( ( built ( by ( slave laborers ) ) ) ( from ( ( Africa , ) ( ( ( whose primary ) employment ) ( was ( on ( sugar plantations ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS levadas)) (VP (VBD were) (ADVP (RB largely)) (VP (VBN built) (PP (IN by) (NP (NN slave) (NNS laborers))) (PP (IN from) (NP (NP (NNP Africa)) (, ,) (SBAR (WHNP (WP$ whose) (JJ primary) (NNS employment)) (S (VP (VBD was) (PP (IN on) (NP (NN sugar) (NNS plantations)))))))))) (. .)))
The levadas were built by the slaves.
( ( The levadas ) ( ( were ( built ( by ( the slaves ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS levadas)) (VP (VBD were) (VP (VBN built) (PP (IN by) (NP (DT the) (NNS slaves))))) (. .)))