Quote Originally Posted by ekaterinak
And one more a slightly smiling thing.
Look at this in following dialog :

Петя: Будешь (хочешь) кофе? / Piter: Do you want some coffee?
Катя: Да нет, наверное. / Kate: Yes, it is not, probably.

What did she mean? Did she say ‘Yes’? Maybe she meant ‘No’ or something else ??????
Actually she meant “No”, but she has been hesitating what she has to say ‘Yes’ or ‘No’.
‘Да нет, наверное’ is soft form of ‘No’. Of course, her answer in English is ‘No, I’m not’.
But maybe she did want to say him the sharp word ‘No’
ekaterinak,
If I am following your thought process correctly... than in English the same conversation might go like this:
Peter: Do you want some coffee?
Kate: "Thanks, that's okay." or "Thanks, but I'm good." or "No, not right now."

In the first two, Kate is saying "thank you" which would seem like yes, but she is actually saying no. In the last one, she is saying "no" yet leaving the door open to maybe have some later. BTW, in the second one, the word "but" is often left out when actually speaking.

Let me know if I missed your point here.