Благодарю вас за объяснения, alexsms!

One other thing for tohca -- remember that you can use the (unstressed) particle же after the word you wish to emphasize:

За что же его благодарить? = WHAT is there to thank him for? or WHY should we thank him?
За что его же благодарить? = What is there to thank HIM for? or Why should we thank HIM?