A.The code runs with no output.
B.An exception is thrown at runtime.
C.Compilation fails because of an error in line 20.
D.Compilation fails because of an error in line 21.
E.Compilation fails because of an error in line 23.
F.Compilation fails because of an error in line 25.

A.3， 2， 1
B.1， 2， 3
C.Compilation fails.
D.The code runs with no output.
E.An exception is thrown at runtime.

A.A,B,C
B.B,C,A
C.Compilation fails.
D.The code runs with no output
E.An exception is thrown at runtime.

A.Arrays.sort（s）；
B.s = new TreeSet（s）；
C.Collections.sort（s）；
D.s = new SortedSet（s）；

A.2，1，0
B.2，1，1
C.3，2，1
D.3，2，2
E.Compilation fails.
F.An exception is thrown at runtime.

A.apple pear
B.banana pear
C.apple apple
D.apple banana
E.banana banana

A.list.add（"foo"）；
B.Object o = list；
C.String s = list.get（0）；
D.list = new ArrayList<String>（）；
E.list = new ArrayList<Object>（）；

A.public class MinMax<？>{
B.public class MinMax<？ extends Number>{
C.public class MinMax<N extends Object>{
D.public class MinMax<N extends Number>{
E.public class MinMax<？ extends Object>{
F.public class MinMax<N extends Integer>{

A.0
B.1
C.2
D.3
E.4
F.Compilation fails.
G.An exception is thrown at runtime.

A.Compilation fails due to an error in line 23.
B.Compilation fails due to an error in line 29.
C.A ClassCastException occurs in line 29.
D.A ClassCastException occurs in line 31.
E.The value of all four objects prints in natural order.

A.public int compareTo（Object o）{/* more code here */}
B.public int compareTo（Score other）{/* more code here */}
C.public int compare（Score s1， Score s2）{/* more code here */}
D.public int compare（Object o1， Object o2）{/* more code here */}