多选题 Given:
2. interface Machine { }
3. interface Engine { }
4. abstract interface Tractor extends Machine, Engine {
5. void pullStuff();
6. }
7. class Deere implements Tractor {
8. public void pullStuff() {System.out.print("pulling "); }
9. }
10. class LT255 implements Tractor extends Deere {
11. public void pullStuff() {System.out.print("pulling harder "); }
12. }
13. public class LTI55 extends Deere implements Tractor, Engine { }
What is the result? (Choose all that apply.)