AIN'T - что за зверь такой?
это слишком разговорное сокращение для am not, is not, are not, has not, have not.
иногда даже для do not, does not, did not. далее справка из Википедии и примеры:
Ain't is an informal contraction for "am not", "is not", "are not", "has not", and "have not". In some dialects ain't is also used as a contraction of "do not", "does not", and "did not". The usage of ain't is a perennial subject of controversy in English. Widely used by many people, and found in most dictionaries, its use is often considered by prescriptionists to be informal, nonstandard, or improper.
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