何回くらい行うかをたずねるときは、How often で始めて、動作の前には do / does（How often do you run?）、気持ちを表すことばの前には is / are（How often are you tired?）を続けます。
How often ＋ do / does
How often do you exercise?
How often does she visit?
How often do they play soccer?
やってみよう: ___ you go to the gym? (How often do / How often / How often are) 答え: How often do — このパターンでは、"How often" のあとに do が必要です：How often do you go? これがないと（"How often you go?"）、疑問文として成り立ちません。
do または does？
文のなかでは、普通の疑問文と同じように選びます。I, you, we, they には do を、he, she, it には does を使います。
How often do you cook?
How often does he cook?
How often do they cook?
Not "How often does you cook?" — say "How often do you cook?". you には do を使います。does は he, she, it のときにとっておきましょう。
やってみよう: How often ___ Amina visit her family? (does / do / is) 答え: does — Amina は1人の人（she）なので、このパターンでは does を使います：How often does Amina visit?（"do" は you/we/they のときに使います。）
頻度で答える
特定の曜日ではなく、何回あるかで答えます：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" は何回あるかをたずねているので、every Monday のような頻度を表すことばで答えます。
やってみよう: How often do you play tennis? 自然な答えを選んでください。 (Twice a week. / At the park. / Yes, I do.) 答え: Twice a week. — "How often" は何回あるかをたずねているので、頻度で答えます：Twice a week。"At the park" は場所を答える表現で、"Yes, I do" は Yes/No 疑問文に答える表現です。
is / are ではなく do / does を使う
動作（go, work, eat）についてたずねるときは、do / does を使います。ここでは is / are を使いません。
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?". do を落とさないようにしましょう。travel のような動作を表すことばには、is / are ではなく do を使います。
やってみよう: How often ___ you eat out? (do / are / is) 答え: do — eat のような動作を表すことばには do が必要です：How often do you eat out? are は気持ちを表すことばにとっておきましょう：How often are you tired?
やってみよう: Ask about Hiroshi's habit. How often ___ he take the bus? (does / do / is) 答え: does — Hiroshi は1人の人（he）なので、does を使います：How often does he take the bus?（he/she/it → does。）
頻度をたずねる
インタビューでは、How often を使って相手の習慣をたずねます。まず How often を置き、次に do か does、そのあとに質問の残りを続けます。
How often do you check your email?
How often does she answer the phone?
やってみよう: Interviewer: ___ you answer the phone at work? Camila: Many times every day. インタビュアーの質問を選んでください。 (How often do / What time do / Where do) 答え: How often do — Camila は「毎日何回も」と回数で答えているので、質問には How often do が必要です: How often do you answer the phone? What time do は時刻を、Where do は場所をたずねる言い方で、どちらも Camila の答えに合いません。
How often are you tired?（be）と How often do you run?（動作）
人を表すことばのあとのことばを見てみましょう。tired のように気持ちやようすを表すことばなら、be を使います: How often are you tired?run のように動作なら、do か does を使います: How often do you run?
How often are you tired? (a feeling, with are)
How often do you run? (an action, with do)
Not "How often do you tired?" — say "How often are you tired?". tired は be のあとに来る気持ちを表すことばなので、質問は do ではなく are のままです。
やってみよう: Amina: Camila works nights. Lars: How often ___ she tired in the morning? Lars のことばを選んでください。 (is / does) 答え: is — Camila は夜に働いているので、朝は疲れていることがあります。Tired は be のあとに来る気持ちを表すことばなので、質問には is が必要です: How often is she tired? does は動作を表すことばといっしょに使い、気持ちには使いません。
やってみよう: Diego: Yasmin does not eat breakfast. Amina: How often ___ she hungry before lunch? Amina のことばを選んでください。 (is / does) 答え: is — hungry は be のあとに来る気持ちを表すことばなので、質問には does ではなく is が必要です: How often is she hungry? does は walk のような動作を表すことばといっしょに使います。