( ( ( ( ( ( The frame ) ( of ( the solenoid ) ) ) ( was ( then attacked ) ) ) and ) ( ( ( the ( iron core ) ) ( ( which part ) ( fills ( the ( central tube ) ) ) ) ) ( was ( drilled out ) ) ) ) . )
(ROOT (S (S (NP (NP (DT The) (NN frame)) (PP (IN of) (NP (DT the) (NN solenoid)))) (VP (VBD was) (VP (ADVP (RB then)) (VBN attacked)))) (CC and) (S (NP (NP (DT the) (NN iron) (NN core)) (SBAR (WHNP (WDT which) (NN part)) (S (VP (VBZ fills) (NP (DT the) (JJ central) (NN tube)))))) (VP (VBD was) (VP (VBN drilled) (PRT (RP out))))) (. .)))
The frame of the solenoid was then attacked and the iron core which part fills the central tube was drilled out.
(ROOT (S (NP (DT An) (NN electormagnet)) (VP (VBZ is) (NP (NP (DT a) (NN piece)) (PP (IN of) (NP (NP (NN iron)) (PP (IN inside) (NP (DT a) (NN solenoid))))))) (. .)))