I thought that you quit teaching English at DMM and was worried.
I thought that you quit teaching English at DMM and was worried, because I hadn't seen you on the page for a long time.
DMMで英語を教えるのを辞めたかと思って心配したよ、だって長い間そのページであなたを見なかったから。
quitは辞めるという意味です。
かなり、という意味のquiteとすごく見た目が似てるので注意してくださいね！
I was worried that you might have resigned from your job at DMM Eikaiwa.
"I was worried that you might have resigned from your job at DMM Eikaiwa." - you are expressing how worried you were at the thought that the teacher might have stopped working for DMM Eikaiwa.
"I was worried that you might have resigned from your job at DMM Eikaiwa."
-「先生がDMM英会話を辞めたのかと思って心配した」と言っています。
There are a few different words that you can use to express your disappointment in thinking that you have lost a teacher.
Here are a few more: "Quit", "disappointed", "concerned", "worried", "upset and "uneasy".
I'd be devastated/distraight if you left the DMM teacher job
By saying 'I'd be' it means how you would feel if something happened
So you would say 'I'd be upset if you left your teaching job' or 'I'd be devastated/distraught' if you left your teacher job'
To be devastated means you are very very upset about it. 'I am worried' means you are upset that something might happen
「I'd be」は、何かがもし起きたとしたら感じることを表します。
したがって以下のように言えます。
I'd be upset if you left your teaching job.
（もし先生が辞めちゃったら困ります。）
I'd be devastated/distraught, if you left your teacher job.
（もし先生がやめちゃったら、すごく悲しい／ショックです。）
「To be devastated」は、すごく動揺していることを表します。
「I am worried」は、何かが起こるかもしれないと心配していることを表します。
I was worried that you might have quit teaching at DMM.
Native speakers will say like this: “I was worried that you might have quit teaching at DMM.”.
There are lots of other ways to say it, but this one is the most accurate and most commonly used.
Here is an example on how to use this in a conversation:
A: Teacher, I'm glad you're online! I was worried that you might have quit teaching at DMM.
B: I was just busy with something. Don't worry!
ネイティブスピーカーなら、このように言うでしょう：
“I was worried that you might have quit teaching at DMM.”
（DMMで教えるのをやめたのかと心配しました）
他にもいろいろな言い方ができますが、これが最も正確で一般的です。
会話で使うと次のようになります：
A: Teacher, I'm glad you're online! I was worried that you might have quit teaching at DMM.
［訳］先生！よかったです。DMMで教えるのをやめたのかと心配しました
B: I was just busy with something. Don't worry!
［訳］ちょっと忙しかったんです。大丈夫ですよ
アメリカ合衆国 
日本 
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