a.Give the regular expression for L, then ={0, 1} and L is the set of all strings x such that a substring '00' must not appear anywhere after a substring '11' in x.

b. Give it regular expression for L when ={a, b} and L={x | x * and x contains at most one occurrence of the substring 'bb'}

c. Give an NFA- for the regular expression (language) in b.