Could you name me any lately changes that can be observed in mordern English tense system? Both standard and colloquial variants. Such as using "will" instead of "shall", using "was" instead of "were" in Conditionals, the word "ain �t" in different senses, etc...
Both are still used in AmE. "I will go to the store." (future, may or may not happen) I shall go to the store. (future, it is going to happen no matter what the obstacle is.) Shall is a bit outdated but among the educated it is still used.
In AmE "gotten" or "got" as a past participle is acceptable. Leaving out the "have" of the perfect tense is only used by the illiterate and maleducated.
I have got my grades just now. (present perfect)
I will have gotten my grades by the time I leave school. (future perfect)
I will have got my grades by the time I leave school. (future perfect still, but doesn �t flow)
I had gotten my homework from Mrs. S-B before my class. (past perfect)
So, from even my own examples, it dawned on me that we in AmE, use gotten in the past and future perfects but not in the present perfect. It �s a flow thing I suppose.
"Was" and "Were" are used in imaginative conditionals.
If I were a director, I would be very strict. (Counterfactual Conditional refers to the present or past but who knows what will happen in the future, but it is a present impossibilty)
If Marcy were to have a job, she would make money. (Hypothetical Conditional refers to present and/or future)
Past tense refers to the present with "were" and "was". "Were" is used for first person and third person as well as second person both singular and plural. It �s an archaic subjunctive throwback.
"Ain �t" - Don �t even go there...it �s just really poor grammar and I would not touch it. To me the use of "ain �t" is ignorance spoken aloud. It means, �the future or present simple of "be" or "have" + not �. I ain �t gonna do no homework. You ain �t gonna have no dinner now. Yes, I have heard these sentences and I cringe. I especially hear it most in the southern USA. So hopefully you ain �t gonna use it. :P