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 10,000 slaves.
( ( The levadas ) ( ( were ( built ( by ( 10,000 slaves ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS levadas)) (VP (VBD were) (VP (VBN built) (PP (IN by) (NP (CD 10,000) (NNS slaves))))) (. .)))