請問為什麼 “在家工作” 的正確英文說法不是 “Work at home” 呢?

感覺正確英文說法是 “Work from home (WFH)” instead of “Work at home”. Is there anyone know the reason?

另外 about “2017”, if it is year, then we always say two thousand seventeen. – (A)

If it is the last 4 digits phone number, then we can say twenty seventeen. – (B).

If it is the password, then we usually say two zero one seven. – [C]

英文語法上 有明顯的定義過 何種情形下 可使用  option (A) or (B) or [C]?  Thanks a lot.

不懂....

我覺得是習慣用法耶, 很難用文法解釋

我一開始也說 work at home, 但聽大家說work from home 久了後也習慣這樣用

年份說法倒是完全沒疑問過, 因為習慣成自然吧