对频度副词提问，英语通常用how often。How often的本意是“多经常”，通常译为“多久”“隔多久”。如：
How often do you wash your hair? 你多长时间洗一次头发?
How often do you go to church? 你隔多久去做一次礼拜?
How often do you have a bad back? 你多长时间腰痛一次?
How often do the buses run? 公共汽车隔多长时间一班?
How often do you hear from your sister? 你多长时间接到你姐姐一次信?
