1. (a+b)*a(a+b)*
2. b*ab*
3. (a+b)*a(a+b)a(a+b)*
4. b*ab*ab*
5. a*
6. (a+b)*ab
7. ab(a+b)*+ba(a+b)*
8. (a+b)*+abba+(a+b)*
9. a(a+b)*a+b(a+b)*b+a+b+
10. (a+b)*a(b+a)*b
11. b*(ab*ab*)*