In Contractions^x, Dialects^x

b is correct. He isn't a good boy Here are the rules for contractions: Apostrophes with Verb Contractions Apostrophes generally show missing letters in contractions. In most formal writing such contractions should be avoided. The most common contractions involve verbs in five situations....

'Annoyed with' here means 'continually bothered by'. So he is answering that indeed he has seen a lot of them. I think it is an exclamation rather than a question: 'I just won the lottery, and am I not delighted!' 'Amn't' is the contraction for 'Am I not', of course. Still current English, I...

>>> "Ain't is also obligatory in some fixed phrases, such as Say it ain't so." Bon Jovi sang "Say it isn't so" From Etymonline: ain't 1706, originally a contraction of am not, and in proper use with that sense until it began to be used as a generic contraction for are not, is not, etc., in...

From Merriam Webster's: AIN'T Etymology: contraction of are not 1 : am not : are not : is not 2 : have not : has not 3 : do not : does not : did not -- used in some varieties of Black English Usage: Although widely disapproved as nonstandard and more common in the habitual speech of the less...

English used to have many regional dialects, and the use of "he does" instead of "he do" was not universal. Also, to pronounce "is" as "ais" and so to get "he ain't" as a contraction of "he aisn't" was a matter of dialect. You also sometimes see amn't. In Jamaican or US "ebonics," even today...