Question

5. When an adverb modifies a verb with a helping verb, the adverb should generally be placed

Answer 1

After the helping verb ,if it's an adverb of frequency
Ex. He doesn't always arrive early.(before the helping verb)

      He never arrives early (as there is no helping verb,the adverb goes before the main verb.

If it's an adverb of place, it goes at the end.
I like to travel to the beach.(where? to the beach)
If it's an adverb of time,it can go either at the end or beginning of the sentence
I'm going to Rio today or
Today, I'm going to Rio;