3. [20 Points] For each of the following languages over a, b design a DFA (a) L w: wE, where w does not have bbb as a substring) (b) L2-(w : w * , where na(w) mod 3-0 and w begins with ab). (c) L,-(vwu : u, w E ., and lul = 2). (d) L4-ab": mn > 4)