( ( The electrode ) ( ( next ( to ( the cathode ) ) ) ( ( is ( the ( control grid ) ) ) . ) ) )
(ROOT (S (NP (DT The) (NN electrode)) (ADVP (JJ next) (PP (TO to) (NP (DT the) (NN cathode)))) (VP (VBZ is) (NP (DT the) (NN control) (NN grid))) (. .)))
The electrode next to the cathode is the control grid.
(ROOT (S (NP (NP (DT The) (NN electrode)) (SBAR (WHPP (IN at) (WHNP (WDT which))) (S (NP (NN reduction)) (VP (VBZ occurs))))) (VP (VBZ is) (VP (VBN called) (NP (DT the) (NN cathode)))) (. .)))