My sons are members of DMM eikaiwa. The older one had a lesson before.
ご質問、誠にありがとうございます！
お母様の立場なので、son「息子」としてしまうのがいいかと思います♩
My sons are members of DMM Eikaiwa. The older one had a lesson before.
「息子たちがDMM英会話の会員で、兄が前にレッスンを受けさせていただきました」
members of 〜 「〜の会員」
older one 「兄が」（sonが前に出ているので、older sonをolder oneとしました)
を使い表現できるかと思います♩
ご参考になられたら幸いです。
My eldest son has had a class with you previously.
Both my sons have English lessons, my eldest has taken a class with you before.
Eldest - another word for oldest.
Previously - at an earlier time, before.
When explaining this situation to a teacher you can simply say 'My older son had a class with you before'
You could also use the above terms, 'My eldest son has had a class with you previously'
To further explain that both your sons have English lessons online you can say 'Both my children have English lessons, my eldest has taken a class with you before'.
Eldest -oldestの別の語です
Previously -より早い時期に、以前に
この状況を先生に説明する時は、ただこう言えば大丈夫です。
例文
'My older son had a class with you before'
兄が以前レッスンして頂きました
上の語を使って、'My eldest son has had a class with you previously'と言うことも出来ます。
2人の息子が両方共オンラインでレッスンをしているとさらに説明するためには、こう言うことが出来ます。
例文
'Both my children have English lessons, my eldest has taken a class with you before'.
子供が2人共英語のレッスンを受けていて、兄が以前レッスンを受けたことがあります
My older son/daughter took your previous lesson.
My older son/daughter took your last class.
These phrases explain that your older child was taught previously by the same tutor.
My older son/daughter took your previous lesson.（兄/姉があなたの授業を受けたことがあります）
My older son/daughter took your last class.（兄/姉があなたの授業を受けたことがあります）
これらのフレーズは、その子の兄/姉が以前同じ先生から教えられたことがあることを表します。
My two sons both take English lessons, my eldest son took a lesson with you before
My eldest son has taken a lesson with you previously
When talking about having two sons the one who is older is called the 'eldest' and the younger one is called the 'youngest'
if you have done somoething before then you would say you have done it 'previously'
You may remember my older son also had lessons with you
If your two sons take online English lessons, and there is a teacher that was very good for your older son, and you want to tell the teacher that your two sons take English lessons and your older son once took a lesson with him/her, then you can express that by using one of the above statements.
We haven't met before. However, both of my sons take online English lessons and the older one once had a lesson with you.
It's the older of my two sons that once took a lesson with you. Both of them take online English lessons.
I have two sons who take online English lessons and the older one once took a lesson with you. He was so impressed with your teaching that he advised me to book a lesson for his younger brother with you.
Since the teacher wanted to know if you had met before, it was imperative to let him/her know that you hadn't met before and then proceed to mention that it was the older of your two sons that once took a lesson with him. You may also mention the fact that both of them take online English lessons. The teacher will be pleased to know that his older son was extremely happy with the way the teacher taught him English that you decided to book a lesson with him for your younger son as well.
So, you may say:
We haven't met before. However, both of my sons take online English lessons and the older one once had a lesson with you.
or
It's the older of my two sons that once took a lesson with you. Both of them take online English lessons.
or
I have two sons who take online English lessons and the older one once took a lesson with you. He was so impressed with your teaching that he advised me to book a lesson for his younger brother with you.
先生に会ったことがあるかどうか確認されたわけなので、まず会ったことがないことを伝えなければなりません。その後、長男がレッスンを受けたことがあることを伝えます。
兄弟どちらも英語のオンラインレッスンを受けていることについて言及してもいいでしょう。
長男がその先生の教え方をすごく気に入ったので次男の予約もその人にしたと分かったら、相手は喜ぶと思います。
次のように言えます。
We haven't met before. However, both of my sons take online English lessons and the older one once had a lesson with you.
（会ったことはありません。ただ、私の二人の息子は英語のオンラインレッスンを受けていて、長男の方はあなたのレッスンを受けたことがあります）
It's the older of my two sons that once took a lesson with you. Both of them take online English lessons.
（二人の息子の長男があなたのレッスンを受けたことがあります。二人とも英語のオンラインレッスンを受けています）
I have two sons who take online English lessons and the older one once took a lesson with you. He was so impressed with your teaching that he advised me to book a lesson for his younger brother with you.
（二人の息子が英語のオンラインレッスンを受けていて、長男の方があなたのレッスンを受けたことがあります。長男があなたの授業に感動して、弟にもあなたのレッスンを受けさせるように私に言ってきました）
Both my sons learn English but my eldest son started learning first
"My Oldest son took your class previously"
'Oldest' is the term used to explain who is the eldest (in age).
'previously' is used when talking about something that had happened in the past tense/before.
"Both my sons learn English but my eldest son started learning first"
'Eldest' is also used to describe the 'oldest'.
"My Oldest son took your class previously"（長男が前にあなたの授業を受けたことがあります）
'Oldest' は年齢が一番上の人を表す言葉です。
'Previously' は過去に起こったことについて言うときに使われます。
"Both my sons learn English but my eldest son started learning first"（二人の息子はどちらも英語を学んでいますが、長男の方が早く学び始めました）
'Eldest' も 'Oldest'（一番年上）を表すときに使われます。
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