Please answer 3a, 3d, and 4a.

3. [12 marks] This question develops your ability to design CFGs. For each of the following languages, give a CFG. Assume the alphabet is = {0, 1). For string x x1x2 . .-Tn, we define xR-Xn . . .X2X1, 1.e. this operation reverses the order of the symbols in a. Justify your answers briefly. n21, (a) {x | x starts and ends with different symbols) (d) {r | r does not contain any substrings of zeroes of odd length}. For example, e, 100, 000011100 are in the language, but 01100 is not. 4. [12 marks] This question develops your ability to design PDAs. For parts (a). (b). (c) of question 3 above, give state diagrams of pushdown automata. For each automata, include a brief description of the idea behind its design