should you buy the movie milk when the tv cow is free 
(ROOT (SQ (MD should) (NP (PRP you)) (VP (VB buy) (NP (DT the) (NN movie) (NN milk)) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (NN tv) (NN cow)) (VP (VBZ is) (ADJP (JJ free))))))))
(ROOT (SQ (MD ) (NP (PRP )) (VP (VB ) (NP (DT ) (NN ) (NN )) (SBAR (WHADVP (WRB )) (S (NP (DT ) (NN ) (NN )) (VP (VBZ ) (ADJP (JJ ))))))))