[biocit]

Well,　I've been teaching my friends Japanese for a bit,and they had a hard time saying "something" desu. Their mouths just can't form around it. They had an easier time pronouncing　んです　than just です。

That's why I have some parts where "ndesu" is used and some where just "desu" is used.

to ossan:

I didn't mean that "watashi" is used consecutively over and over in one conversation. I'm just saying it is generally used.