memorandum

他写了一份备忘录提醒自己明天要开会。

He wrote a ___memorandum to remind himself of tomorrow's meeting.

我在便利贴上写了个备忘录提醒自己买牛奶。

I wrote a ___memorandum on a sticky note to remind myself to buy milk.

我写了一份备忘录提醒自己明天要交报告。

I wrote a ___memorandum to remind myself about the report due tomorrow.