Not "They has two children." — say "They have two children.". Has は he, she, it のときだけで、they のときは have を使います。
やってみよう: They ___ two children. (have / has / haves) 答え: have — 「has」を選んだ場合、その形は he/she/it のときだけです。they のときは have を使って They have two children とします。
He / she / it: has
he, she, it のときは has を使います。
He has a bike.
She has brown eyes.
The cat has four legs.
Not "She have brown eyes." — say "She has brown eyes.". Has は he, she, it であることを表す形です。
やってみよう: Matilda ___ a dog. (has / have / haves) 答え: has — Matilda ＝ she なので has を使います。
have それとも has？
選ぶ前に「だれ？」と考えてみましょう。he/she/it → has、I/you/we/they → have です。
He has a car. / They have a car.
She has time. / We have time.
Not "He have a car. / They has a car." — say "He has a car. / They have a car.". 同じ単語でも、主語によって have か has かが決まります。
やってみよう: Hiroshi ___ a book. Amina and Mei ___ a book. (has … have / have … has / has … has) 答え: has … have — Hiroshi ＝ he → has。Amina and Mei ＝ they → have。
否定文: don't have
I, you, we, they のときは don't have を使います。
I don't have time.
We don't have a car.
They don't have a key.
Not "I don't has time." — say "I don't have time.". don't の後ろでは動詞が have に戻り、has になることはありません。
やってみよう: We ___ a dog. (don't have / doesn't have / don't has) 答え: don't have — we のときは don't を使い、don't の後ろは have になります。
否定文: doesn't have
he, she, it のときは doesn't have を使います（変化が doesn't に移動します）。
He doesn't have a car.
She doesn't have time.
Not "She doesn't has a car." — say "She doesn't have a car.". Doesn't がすでに変化を引き受けているため、動詞は have に戻ります。
やってみよう: Liam ___ a pen. (doesn't have / doesn't has / don't have) 答え: doesn't have — Doesn't がすでに -s を引き受けているので、動詞は have になります。
疑問文: Do / Does ＋ have
文頭を Do（I/you/we/they）または Does（he/she/it）にして、そのあと have を置きます。
Do you have a pen?
Does she have a car?
Not "Does she has a car?" — say "Does she have a car?". Does の後ろは have になります。変化はすでに Does に含まれているからです。
やってみよう: ___ Sofia have a pen? (Does / Do / Is) 答え: Does — Sofia ＝ she なので、質問は Does から始めます。
やってみよう: Remember: who is it? Mei ___ three books. (has / have / haves) 答え: has — Mei ＝ she → has。（これがすべての基礎となる選択です: he/she/it → has。）