feel that we truly know what makes holly and marina tick 
(ROOT (S (VP (VB feel) (SBAR (IN that) (S (NP (PRP we)) (ADVP (RB truly)) (VP (VBP know) (SBAR (WHNP (WP what)) (S (VP (VBZ makes) (S (NP (NN holly) (CC and) (NN marina)) (VP (NN tick))))))))))))
(ROOT (S (VP (VB ) (SBAR (IN ) (S (NP (PRP )) (ADVP (RB )) (VP (VBP ) (SBAR (WHNP (WP )) (S (VP (VBZ ) (S (NP (NN ) (CC ) (NN )) (VP (NN ))))))))))))