So, in no way they are interchangeable...hehe  Isn´t it so, Dale?

  Just asking; since Angela asked if they wether the expressions were or not.

  You know, sometimes Brazilians (me included) usually don´t understand indirect answers...(kidding around, Dale.)

   You answer, as always, was great.  But answering the direct question I would risk no, they aren´t interchangeable. If I didn´t miss something.

   Angela never let us know if her doubt persisted or was cleared up, that´s why I insisted...you know, sometimes people don´t grasp the meaning of the answer and put a "I understood everything you said" face, and agree to the person that answered, but when the guy leave he/she turn to the nearest friend, coworker, classmate and ask what he meant?

   This happened a lot in my English classes, and it was my nightmare every time the teacher left, even to drink some iced water nearby!

   As some things never change, I explain some topic on Maths, Science, Portuguese, whatever you have; to my children and they say I understood, that´s okay.

   Then I say, now you are going to do some exercise...  I can see the big question mark above their heads!