So does this refer to past tense or present tense?
It is present passive.
I should have reviewed English grammar before starting this course. It has been so long, well over a half century, that I was taught grammar, that I have forgotten most of it and here I am playing catch up in another language.
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"I read that book." Not passive thus incorrect here.
The speaker needs to say 'bởi' more slowly, it sounds too much like 'của'