is it entirely necessary to have “没有” for negative past verbs, or can you omit "有“? "为什么你没告诉我?"
It is acceptable to omit 有 here.
And a follow up question, can you replace 没有 with 不 in this case, or no? And why?
If you replaced the meiyou with bu, you would instead be saying 'Why don't you tell me?' or 'Why aren't you telling me?'
不 is current or future tense, 没有 is for past tense
No I don't think 不 is acceptable in this case as 没 is the negation word used when talking about past events. Replacing 没 with 不 would change the meaning of the sentence from past tense to present tense.
Not necessary, 没 is enough
你们 and but no mention of group in the question?
Please replace 你们 for 你.
There is no 你。 The right answer is “为什么你没有告诉我”。 But there is only “你们” as an option
Did anyone notice that there was no 你 by itself, only 你们? At least for me. They accepted it, but it's a misprint.
「你為啥沒告訴我」should be accepted