though he only scratches the surface 
(ROOT (SBAR (IN though) (S (NP (PRP he)) (ADVP (RB only)) (VP (VBZ scratches) (NP (DT the) (NN surface))))))
(ROOT (SBAR (IN ) (S (NP (PRP )) (ADVP (RB )) (VP (VBZ ) (NP (DT ) (NN ))))))