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8th day of the month
eight days
八日の夕方に届く予定だ。
It's scheduled to arrive on the evening of the 8th.
来月の八日は祝日だから休みだよ。
The 8th of next month is a holiday so we have the day off.
八日に出した書類がまだ戻ってきていない。
The documents I submitted on the 8th haven't come back yet.