Let L(R) be the language represented by regular expression R. Let L(G) be the language generated by a context free grammar G. Let L (M) be the language accepted by a Turning machine M. Which of the following decision problems are undecidable?
I. Given a regular expression R and a string w, is ?
II. Given a context-free grammar G, 
III. Given a context-free grammar G, is for some alphabet 
IV. Given a Turning machine M and a string w, is