Need help with the last 4 parts E,F,G and H.

1. Give regular expressions generating the following languages over the alphabet ? = {a,b): a) {w w begins with a and ends with a} b) { ww contains at least 3 a's} c) {ww contains the substring abba} d) {w w has the length at least 3 and its third symbol is a} e) {ww starts with a and has odd length, or starts with b and has even length} f) {w the length of w is at most 6} g) {w w is any string except aaa and bb} h) {wlw is any string that has second last symbol equal to b}