Parents must ask questions like  
( Parents ( must ( ( ask questions ) like ) ) )
(ROOT (S (NP (NNS Parents)) (VP (MD must) (VP (VB ask) (NP (NNS questions)) (PP (IN like))))))
Parents should never ask any questions
( Parents ( ( should never ) ( ask ( any questions ) ) ) )
(ROOT (S (NP (NNS Parents)) (VP (MD should) (ADVP (RB never)) (VP (VB ask) (NP (DT any) (NNS questions))))))