欠席届け
absence without due notice―absence without leave
to absent oneself without due notice―play truant
to absent oneself without due notice―play truant
無断欠席する
to absent oneself without due notice―absent oneself without leave―play truant
寄留届け
You should not be absent without notice.
Unavoidable circumstances obliged me to absent myself.
I must absent myself from school because I am ill―on account of illness―(他動詞構文にすれば)―Illness obliges me to absent myself from school―Illness prevents me from attending school―Illness prevents my attendance.
My absence is justifiable―excusable.
Please reply only if you cannot attend.