多选题 Given:
3. class Bonds {
4. Bonds force() {return new Bonds(); }
5. }
6. public class Covalent extends Bonds {
7. Covalent force() {return new Covalent(); }
8. public static void main(String[] args) {
9. new Covalent() .go(new Covalent());
10. }
11. void go(Covalent c) {
12. go2(new Bonds() .force(), c.force());
13. }
14. void go2(Bonds b, Covalent c) {
15. Covalent c2 = (Covalent)b;
16. Bonds b2 = (Bonds)c;
17. } }
What is the result? (Choose all that apply.)