Should I write "before I know it" or "before I knew it" when speaking in the present tense?
Example sentence:
"This boss is too tyrannical. Before I know it/before I knew
it, I'll/I'd become his slave."
I chose the first version, but a native English speaker told me I should use the second.
Best Answer
The answer here is shown by the verb tenses you're using for the rest of the sentence. (and you did get the verb tenses correct, BTW, which many people don't, so good job on that!)
This is perfectly correct, but it is a future tense sentence. It says that you will become his slave in the future, and that when that happens, you expect it will be true before you actually realize it.
Here, you need to use the past tense "knew", because your main verb ("had become") is in a past tense. This whole thing is, therefore, describing something that happened in the past. You already have become his slave, and it happened before you knew it.
So the answer is: You can use either one, but which one you use should depend on whether you want to talk about a past thing or a future thing.