1 -----------------

  output is 

   ra1 fails test
   abcba

2 -----------------

  public static void downTo(int num) {
    if (num >= 0) {
      System.out.println(num);
      downTo(num-1);
    }
  }

3 -----------------

  downTo(10);

4a ----------------

  7 40 13 25 90

4b ----------------

  25 13 7 40 90

5a -----------------

  17 13 15  

5b ------------------ 

  23 13 29 31 20

6 ------------------

  binary

7 ------------------

  Object

8a -----------------

  toString, clone, equals

8b ------------------

	none

	student super, TA sub

	blue jay sub, bird super

9a ------------------

	Comparable

9b ------------------
	
	1) true
	2) false
	3) true
	4) true
	5) false
	6) true