多选题 Given:
5. class OOthing {void doStuff() {System.out.print("oo "); } }
6. class GuiThing extends OOthing {
7. void doStuff() {System.out.print("gui "); }
8. }
9. public class Button extends GuiThing {
10. void doStuff() {System.out.print("button "); }
11. public static void main(String[] args) {new Button().go();}
12. void go() {
13. GuiThing g = new GuiThing();
14. // this.doStuff();
15. // super.doStuff();
16. // g.super.doStuff();
17. // super.g.doStuff();
18. // super.super.doStuff();
19. } }
If the commented lines are uncommented independently, which are true? (Choose all that apply.)