0 to write the necessary information on an official document -- 填写(正式文件)
to fill in a form/questionnaire 填写表格/调查问卷
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.
再长的路,一步步也能走完,再短的路,不迈开双脚也无法到达。