Given:
2. public class Clover extends Harrier {
3. String bark() {return "feed me "; }
4. public static void main(String[] args) {
5. Dog[] dogs = new Dog[3];
6. dogs[0] = new Harrier();
7. dogs[1] = (Dog)new Clover();
8. dogs[2] = (Dog)new Harrier();
9. for(Dog d: dogs) System.out.print(d.bark());
10. } }
11. class Dog {String bark() {return "bark "; } }
12. class Harrier extends Dog {String bark() {return "woof "; } }
What is the result (Choose all that apply.)

单项选择题Given:2. import java.util.*;3. public class GIS {4. public static void main(String[] args) {5. TreeMap＜String, String＞ m1 = new TreeMap＜String, String＞();6. m1.put( a , amy ); m1.put( f , frank );7. NavigableMap＜String, String＞ m2 = m1.descendingMap();8. try {9. m1.put( j , john );10. m2.put( m , mary );11. }12. catch (Exception e) {System.out.print( ex ); }13. m1.pollFirstEntry();14. System.out.println(m1 + + m2);15. } }What is the result

单项选择题Given:14. FileWriter fw1 =new FileWriter(new File( f1.txt ));15. FileWriter fw2 =new FileWriter(new BufferedWriter(new PrintWriter( f2.txt )));16. PrintWriter pw1 =new PrintWriter(new BufferedWriter(new FileWriter( f3.txt )));17. PrintWriter pw2 =new PrintWriter(new FileWriter(new File( f4.txt )));And given the proper imports and error handling, what is the result