I always believed the word 'have' follows any future or past verb tense but, unfortunately, some people don't know what a verb is, never mind a tense! Luckily, my 8 year old granddaughter attends a very good school, where written grammar and spelling along with good numeracy skills are seen as desirable things to strive for. I am also encouraging her to proofread her homework.
There are so many easy ways to remember things to help correct spelling but wonder if schools teach them. For instance words which go together like hear/ear and here/there, or that plurals don't need apostrophes unless it denotes a possessive. Duh, what's a possessive?
I must admit I hadn't heard of tautology and had to look it up even though I was grammar school educated and took Latin to A level, so always glad to learn something new. Although, surely repeats can be used to stress something.