Wastewater treatment plant operator question I keep getting wrong on WASTEWATER practice tests

There's a category of question on my Wastewater Operator Certification practice tests that I'm consistently missing and I can't figure out what I'm misunderstanding.

The questions are about wastewater treatment plant operator. Here's the type of question that trips me up: they give me a scenario and ask what the right action is, and I usually narrow it down to 2 answers — then pick the wrong one.

I think my issue is I'm applying the general rule but not accounting for the exception. Can anyone point me to a good explanation of when the standard rule doesn't apply for wastewater treatment plant operator?

I've looked at "wastewater operator" study materials but they explain the concept at the surface level. I need the deeper "why" behind it.

Any specific resources, videos, or even just a plain English explanation would be genuinely helpful. Exam is in 4 weeks.