( ( ( A ( drop keel ) ) ( ( containing transducers ) ( for ( ( the measurement ) ( of ( plankton ( density ( and ( ocean currents ) ) ) ) ) ) ) ) ) ( ( can ( be ( ( lowered ( 3 ft ) ) ( below ( ( the bottom ) ( of ( the ship ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (NN drop) (NN keel)) (VP (VBG containing) (NP (NNS transducers)) (PP (IN for) (NP (NP (DT the) (NN measurement)) (PP (IN of) (NP (JJ plankton) (NN density) (CC and) (NN ocean) (NNS currents))))))) (VP (MD can) (VP (VB be) (VP (VBN lowered) (NP (CD 3) (NN ft)) (PP (IN below) (NP (NP (DT the) (NN bottom)) (PP (IN of) (NP (DT the) (NN ship)))))))) (. .)))
A drop keel containing transducers for the measurement of plankton density and ocean currents can be lowered 3 ft below the bottom of the ship.
(ROOT (S (NP (JJ Deep) (NNS currents)) (VP (VBP are) (VP (VBN caused) (PP (IN by) (NP (NP (NNS differences)) (PP (IN in) (NP (NN density))))) (PP (IN at) (NP (NP (DT the) (NN top) (CC and) (NN bottom)) (PP (IN of) (NP (DT the) (NN ocean))))))) (. .)))