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Throughout highschool and college I was told "n't" (e.g. can't, wouldn't, shouldn't) should not be used in essays. The manner of which the use of "n't" was bastardized by many people who I considered to hold authority in the manner of the English Language.
I pose the question of what do all of you think of the use of "n't" and in what cases should it be used or avoided. I ask this because I feel that writing an email or a short essay saying "don't" is not a big deal, yet people make it one and I do not know why they do this.