现有：  import java.util.*；      class AddStuff2  {  public static void main（String  []  args）  {      TreeSett=new TreeSet（）；      if （t.add（"one"））      if （t.add（"two"））     if （t.add （"three"））  add（"four"）；  for （String s  ：  t）      System.out.print （s）；     }      }      结果为：（）     

• A、 one
• B、 one three two
• C、 one two three
• D、 one two three four
• E、 four one three two
• F、编译失败