該做的事沒做
空缺的位置從「名單上的一項」換成「該做的一件事」：那個動作本來應該發生，結果沒有發生。
fail to do · verb · C1
in the phrase 'omit to do something': to not do a thing you were supposed to do, either because you forgot or because you chose not to.
（正式）沒有去做；忘了做
核心畫面
One way to picture omit: something that could have been included simply is not there — a name missing from the list, a paragraph left out of the report. English does not say whether it was deliberate or an oversight; the word only marks the gap, which is why it feels neutral and slightly formal.
可以想成 omit 是「本來可以放進去的東西，就是不在裡面」：名單上少了一個名字、報告裡少了一段。英文沒有說那是刻意…更多收起
可以想成 omit 是「本來可以放進去的東西，就是不在裡面」：名單上少了一個名字、報告裡少了一段。英文沒有說那是刻意還是疏忽，這個字只標示那個空缺——所以它聽起來中性，而且帶點正式感。From the picture
Also in this word
leave out · verb · C1
to not put someone or something in — you leave them out of a list, a story, or a piece of writing, either on purpose or because you forgot.
省略；漏掉
原始詞典資料4 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
omitverb/əʊˈmɪt/
- 1
To leave out or exclude.
- 2
To fail to perform.
- She climbed out of the car and carefully omitted to lock it. She never left anything of value in it, and she found that it was to her advantage if people didn’t have to break anything in order to find that out.
- 3
lawTo delete or remove; to strike.
- In the Criminal Justice and Public Order Act 1994, omit sections 146(4) and 147(3) (homosexual acts as grounds for dismissal from the crew of merchant ships).
- 4
rareTo neglect or take no notice of.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。