is it all right to contract "I am not" to "I'm not" or "I amn't"
a) in formal style
b) in informal style?
I'm not is fine in speech and informal writing.
Many thanks to you!
***NOT A TEACHER ***
(1) There is no contraction for "am not" in "good" English.
That is why people must say:
I am your best friend, am I not?
I am your best friend, aren't I? (Yes, I know that "aren't" does not
match "I," but that is just one of the inconsistencies found in language.)
(2) Yes, there is a contraction for "am not," but today most (not all)
people feel that it is bad English: ain't. If you use this word,
most (not all) Americans will feel that (a) you are not well-educated
or (b) you are trying to be funny (making a joke). I most respectfully
suggest that you NOT use it. When you become fluent in English, then
you can occasionally use it for a humorous effect.