ask for three-days' leave有错吗

I want.to ask for three days leave 为什么ask for three days' leave 中days'要用逗号? ask for three days 'sick ask for days' leave 疑问句还用加'么 for的用法:如so i'd like to ask for three days leave中for 的用法.例举其他 My I ask for (3day,3 days') leave our family _____(leave) for shanghai in three days Mr.Black is___(leave)for Shanghai in three days. 请假用ask还是ask for,比如请三天假是ask thee days off 还是 ask for three da after three days,they will be coming有错吗? They_____london for three days. She wants to ask for two days' leave改为同义句