From the old days, I was taught to use nor this way:
"They don't know how to do x nor do they know how to do y."

In Kaplan, the correct answer of the question says "They don't know how to X or how to Y."

One of the incorrect answer choices is "They don't know how to X nor how to Y."

I'm wondering why the nor answer choice is incorrect. Obviously, the structure is different than what I learned in the old days.