1. I read comic books, eating some snacks.
2. I read comic books while /as I ate some snacks.
3. I read comic books and ate some snacks.
4. I read comic books and ate some snacks at the same time.
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Are they all the same and grammatical?
Does #3 mean #1 without adding 'at the same time' at the end?
3 answers
Is "read" in these sentences intended to be the past tense? (pronounced "red")
Yes. It's the past tense.
All the sentences are fine. They'd be better if you added "Last night" or some other phrase that indicates past tense.