Excuse me but I could not understand the first part. I used "could" as a past modal that expresses past ability as in "I could read fast when I was young", not as a present modal that expresses possibility or hypotheticality, as in "I am so angry I could fling out right now" or "It could be true but we have to wait to see what'll happen".
In this respect, what makes "could" in the first clause a present tense modal in the sentence "I could read my books but I did not" ?
anonymous I used "could" as a past modal Maybe that was your intent, but native speakers don't try to read the writer's mind when it comes to grammatical matters such as fluent tense sequences. They will read the sentence, know it was not written by a native speaker and make allowances.
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anonymousI used "could" as a past modal
Maybe that was your intent, but native speakers don't try to read the writer's mind when it comes to grammatical matters such as fluent tense sequences. They will read the sentence, know it was not written by a native speaker and make allowances.