Can Somebody help me a bit with the Talmud?

I am Israeli and I speak modern Hebrew natively. I’ve been reading more and more of the Tanakh and as such I’ve been getting used to Biblical Hebrew. Recently I’ve been studying the book of Job. During my studys I’ve come across a pretext from the Talmud with which I need help understanding:

Babylonian Talmud, Baba Batra 16, pages 1-2:

בין גומא לגומא לא נתחלף לי. בין איוב לאויב נתחלף לי?…

בין קול לקול לא נתחלף לי. בין אויב לאיוב נתחלף לי?…

בין רגע לרגע לא נתחלף לי. בין איוב לאויב נתחלף לי?

I’m mainly having trouble understanding the meaning of the word נתחלף (In modern Hebrew “to change”). My modern Hebrew doesn’t give me any clue to how it fits this pretext and as such I don’t understand the gist of it.

Thanks for helping!