However, their cumulative effect tends to be overpowering.
( However ( , ( ( their ( cumulative effect ) ) ( ( tends ( to ( be overpowering ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB However)) (, ,) (NP (PRP$ their) (JJ cumulative) (NN effect)) (VP (VBZ tends) (S (VP (TO to) (VP (VB be) (ADJP (JJ overpowering)))))) (. .)))
Only when put together are the effects overpowering.
( ( ( Only when ) ( put together ) ) ( ( are ( ( the effects ) overpowering ) ) . ) )
(ROOT (S (SBAR (WHADVP (RB Only) (WRB when)) (S (VP (VBD put) (ADVP (RB together))))) (VP (VBP are) (NP (NP (DT the) (NNS effects)) (VP (VBG overpowering)))) (. .)))