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with; by; by means of
because of; on account of; for; due to
on (a day, date); at (a time); as of (e.g. today)
本日を以て退職いたします。
I will resign as of today.
誠意を以て対応させていただきます。
Allow us to respond with sincerity.
この書面を以て正式な通知とする。
This document shall serve as the official notice.