# 英语冠词 a 与 an 的例外规则：32455 个单词中仅 129 个需特殊处理

- 来源：Hacker News 热门（buzzing.cc 中文翻译）
- 作者：azhenley
- 发布时间：2026-09-20 08:13
- AIHOT 分数：22
- AIHOT 链接：https://aihot.news/items/cmu92ktj305ljrojrv8zuypdn
- 原文链接：https://www.redblobgames.com/blog/2026-09-16-english-a-vs-an

## AI 摘要

英语冠词 a/an 的选择取决于读音而非首字母，unicorn 用 a、hour 用 an 即为例外。作者用一天时间分析 32455 个单词，发现仅 129 个需要例外处理，并据此构建可视化，判断前两个字母是否足以决定用 a 还是 an。

## 正文

In English, there is an "indefinite" article a that can go before a word. For example, a raccoon. But for some words, we use an. For example, an apple. When procedurally generating text, I want a function a_or_an("apple") that tells me which article to use. That seems like it'd be easy. We can check the first letter to see if it's a vowel. But that would mean we output an unicorn, not a unicorn. The actual rule is not whether the written word starts with a vowel letter, but whether the spoken word starts with a vowel sound. The word unicorn starts with vowel letter (u) but a consonant sound (Y).

The word hour starts with a consonant letter (h) but a vowel sound (OW). Visualization showing whether the first two letters of a word are enough to determine whether it should have "a" or "an" I was curious how often these exceptions occurred, and whether they can be grouped together, so I spent a day looking at the data and building some visualizations and wrote up the results. I was surprised that only 129 of the 32,455 words in my list needed exceptions. [LLM note: I did not use LLMs to write any of this code, but in hindsight, I should have.

This is one-off code to answer a question. It doesn't need to be clean or maintainable. It only needs to be correct. I would've spent more time on the trie simplification algorithm and less time on parsing cmudict and re-learning d3.js.]