Choose the most effective revision for the underlined part of the sentence. if no revision is necessary, choose "leave it as is."

we rise the flag in the morning and then take it down before the sun sits at night.

It seems that you have forgotten to indicate the underlined part of the sentence, but there is only one thing I have noticed in the given sentence above that needs to be revised. It is the part "rise" and "sits at night". This is the revised sentence: We raise the flag in the morning and then take it down before the sun sets. Hope this answer helps.