Question

She (visit) her sister across the street once a week.

Answer 1

once a week she visit her sister across the street.
hope this would help u

Answer 2

Answer:

she visits her sister across the street, twice a week.

Explanation:

we cannot say she is visiting her sister across the street, twice a week, because she is continuing now she is doing that so we can't write she is visiting her sister across the street, twice a week .