问一件事多久发生一次，先用 How often do 或 How often does 开头，再接上问题的其余部分。
How often + do / does
How often do you exercise?
How often does she visit?
How often do they play football?
试一试: ___ you go to the gym? (How often do / How often / How often are) 答案: How often do — 这个句型需要在 "How often" 后面加 do：How often do you go? 少了它（"How often you go?"）句子就不完整。
Not "How often does you cook?" — say "How often do you cook?". you 用 do。does 只留给 he、she、it。
试一试: How often ___ Amina visit her family? (does / do / is) 答案: does — Amina 是一个人（she），所以这里用 does：How often does Amina visit?（"do" 是给 you/we/they 用的。）
用频率来回答
要用多少次来回答，而不是某一天：every day、twice a week、usually、never。
How often do you exercise? Three times a week.
How often does she visit? Every weekend.
How often do they meet? Usually on Fridays.
Not "How often do you go? On Monday." — say "How often do you go? Every Monday.". "How often" 问的是次数，所以要用像 every Monday 这样的频率来回答。
试一试: How often do you play tennis? Pick the natural answer. (Twice a week. / At the park. / Yes, I do.) 答案: Twice a week. — "How often" 问的是次数，所以要用频率来回答：Twice a week. "At the park" 回答的是地点；"Yes, I do" 回答的是是非问句。
用 do / does，不用 is / are
说到动作（go、work、eat）的时候，句型用 do / does。这里不要用 is / are。
How often do you travel?
How often does he call?
How often do they visit?
Not "How often you travel?" — say "How often do you travel?". 别漏掉 do。像 travel 这样的动作词，句型里要用 do，不是 is / are。
试一试: How often ___ you eat out? (do / are / is) 答案: do — 如果你选了 are，How often 这个句型不能用它。像 eat 这样的动作词需要 do：How often do you eat out?
试一试: Ask Hiroshi about his habit. How often ___ he take the bus? (does / do / is) 答案: does — Hiroshi 是一个人（he），所以这里用 does：How often does he take the bus?（he/she/it → does。）