farmworkers conducted by the U.S.
( farmworkers ( conducted ( by ( the U.S. ) ) ) )
(ROOT (S (NP (NNS farmworkers)) (VP (VBN conducted) (PP (IN by) (NP (DT the) (NNP U.S.))))))
Some farm laborers were sampled.
( ( Some ( farm laborers ) ) ( ( were sampled ) . ) )
(ROOT (S (NP (DT Some) (NN farm) (NNS laborers)) (VP (VBD were) (VP (VBN sampled))) (. .)))