About Question enthuware.ocajp.i.v7.2.1334 :

[ETS User]

In constructor
B(String s){ super(s, " world "); }

It looks like there is a space after world.
I know it's trivial but if you had an option with none of the above I would have chosen that because I thought "good bye world " would be printed.
Thanks.

[ml.vilen]

there is an extra space in this question
B(String s){ super(s, " world "); }
please fix it

[admin]

Fixed.
thank you for your feedback!