how often 的用法：“多久，次数”how often用来提问某动作或状态发生的频率，对“一段时间内发生了几次活动”（always，usually， often， never或twice a day等表示频度的词或短语）提问时用有关频率的问题多用How often如 How often do you take a shower? how often do you do landry?多长时间干一次什么事。How often do his parents let him watch TV? 他父母多久让他看一次电视？
