The war of language acquisition

Due to serious infirmities and creeping neurological deterioration, this may be one of my last posts in this blog. I just wanted to let you know, in case.

Language learning and teaching is like a war. A battlefield with two contenders: the teacher and the pupil.
The pupil is on the defense,and will use all her might and tricks to stop the instructor from winning the battle. Students are very stubborn and disobedient and usually refuse to change their ways, grammatical or  phonetical.
The instructor starts the battle, the first day of class, with glee and interest. His aim is to teach the language and he presupposes that pupils want to learn, that is why they come to class and pay tuition.
Reality, the bolts and nuts of life, dictates otherwise.
I have been telling students that "people" in English is plural, and so we must say "people are," "people have," to no avail.
I tell them, again and again and again, to pronounce the ts (department, tent, twenty) and their ds (blended, understand, fad) again to no avail.
I try and try and try and never give up... and my students put up a valiant fight. But I tell them I will never tire of correcting and that it is easier for them to try harder and accept the corrections than hearing me repeat again and again and again.
My advice:
Pupil: do not put up a fight and let your teacher win.
Teacher: Never give up in despair, insist and teach.
The only value in having a teacher is that she corrects us. A teacher who does not correct is not a teacher worth his salt.