Give regular expression for the following over alphabet (a,b)

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) {w|w contains the substring abba} d) { ww has the length at least 3 and its third symbol is a} e) { w[w 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) { ww is any string except aaa and bb} h) { ww is any string that has second last symbol equal to b}