( ( An ( electrical insulator ) ) ( ( is ( ( a material ) ( that ( resists ( ( the flow ) ( of ( electric current ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT An) (JJ electrical) (NN insulator)) (VP (VBZ is) (NP (NP (DT a) (NN material)) (SBAR (WHNP (WDT that)) (S (VP (VBZ resists) (NP (NP (DT the) (NN flow)) (PP (IN of) (NP (JJ electric) (NN current))))))))) (. .)))
An electrical insulator is a material that resists the flow of electric current.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (NNS materials)) (SBAR (WHNP (WDT that)) (S (VP (VBP have) (NP (JJ high) (NN resistance)) (PP (TO to) (NP (JJ electric) (JJ current) (JJ electric) (NNS insulators)))))))) (. .)))