is about as necessary as a hole in the head 
(ROOT (VP (VBZ is) (ADJP (ADJP (RB about) (RB as) (JJ necessary)) (PP (IN as) (NP (NP (DT a) (NN hole)) (PP (IN in) (NP (DT the) (NN head))))))))
(ROOT (VP (VBZ ) (ADJP (ADJP (RB ) (RB ) (JJ )) (PP (IN ) (NP (NP (DT ) (NN )) (PP (IN ) (NP (DT ) (NN ))))))))