How long have you been with the company? - this is more formal
How long have you been working here? - this is used more often in casual conversation
A. So, how long have you been working at Google?
B. About 8 years.
A. Do you like it there? I hear the work environment is so relaxed.
B. Yeah, it's pretty chill.
How long have you been with the company? - これはよりフォーマルな表現です。
How long have you been working here? - これはよりカジュアルな会話で使われる表現です。
【例文】
A. So, how long have you been working at Google?（Googleでどれくらい働いているの？）
B. About 8 years.（8年くらい）
A. Do you like it there? I hear the work environment is so relaxed.（Googleを気に入っている？職場環境がとてもリラックスしていると聞いたけど）
B. Yeah, it's pretty chill.（うん、なかなか落ち着いているよ）
You may use the present pefect form (have you worked) or the present perfect continuous form (have you been working) in this case. This employee is clearly working at the present time, and the present perfect form connects the present with the immeditely preceeding period of time.
A: "What have you been doing today?"
B: "Well, I collected my passport from the post office earlier today, and I've been preparing the vegetables for our evening meal."
この場合は(have you worked) という現在完了形か(have you been working)という現在完了進行形を使うことが出来ます。
この従業員は明らかに現在も働いているので、現在完了形が、現在とすぐ前の期間をつなぎます。
例文
A: "What have you been doing today?"
今日は何をしていたの？
B: "Well, I collected my passport from the post office earlier today, and I've been preparing the vegetables for our evening meal."
今日は早くに郵便局にパスポートを取りに行って、夕食用の野菜の下ごしらえをしていたの。
*How long have you been working here?
This means you want a time period e.g number of years, months or days (whichever is applicable)
For example:
You:How long have you been working here?
Co-worker: It has been about 2 years now.
例文
*How long have you been working here?
ここでどれくらい働いているの？
期間を知りたいと言うことです。例 年数、月数、日数（どれでも大丈夫です。）
例文
You:How long have you been working here?
ここでどれくらい働いているの？
Co-worker: It has been about 2 years now.
現在でおよそ2年です。
A) How long have you been working here ?
*How long -Duration of time
Example- How long will Lucy be?
*Working-having paid employment.
Example-"the size of the working population"
*Here-in, at, or to this place or position.
Example-"they have lived here most of their lives"
B) When did you start working here ?
*When-at what time.
Example-"when did you last see him?"
*Start-begin or be reckoned from a particular point in time or space; come into being.
Example-"the season starts in September"
I hope this helps :-)
例文
A) How long have you been working here ?
ここでどれくらい働いていますか？
*How long -時間の長さ
例文
How long will Lucy be?
どれくらいルーシーはいますか？
*Working-賃金が支払われる雇用
例文
"the size of the working population"
労働人口の大きさ
*Here-この場所、位置
例文
"they have lived here most of their lives"
彼らは人生の大部分をここで暮らしてきた。
例文
B) When did you start working here ?
ここで働き始めたのはいつですか？
*When-何時に
例文
"when did you last see him?"
彼を最後に見たのはいつですか？
*Start-始める、特定の時間、場所から起算して；生じる
例文
"the season starts in September"
その季節は9月に始まる。
お役に立てば幸いです。
「いつから」→「Since when」
「ここ」→「Here」
「務める」→「To work」
「Since when have you been working here?」→「いつからココに勤めているの」
「When did you start working here?」は、
少しだけニュアンスが変わります。
「いつここに働き始めたの？」という意味です。
If you would like to ask someone how long they have been working somewhere, you can ask them by saying something like "When did you start work here?" or "How long have you been working here?".
どれくらい働いているかを聞きたいときのフレーズです。
"When did you start work here?"
（ここでいつ働き始めましたか？）
"How long have you been working here?"
（ここでどのくらい働いていますか？）
When you want to ask a person how long they have been working at a particular shop/restaurant/etc.; then you may ask in the following ways:
-When did you start working here?
-How long have you been working here?
人にどれくらいそのお店やレストランなどで働いているのかを尋ねたいときのフレーズです。
-When did you start working here?
（ここでいつ働き始めましたか？）
-How long have you been working here?
（ここでどれくらい働いていますか？）
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