定义 / 说明
语域（register）是根据场景、关系和目的选择语法与词汇。C1 阶段，语法本身就能标记语域：缩写、短句、直接问句、短语动词常更口语；完整形式、名词化、某些从句模式常更正式。比如 It's really important that... 偏中性，而 It is essential that... 更正式、更机构化。良好语域控制意味着在不改变核心意义的前提下灵活换风格。
关键规则
- 非正式英语常用缩写、日常动词、较短结构。
- 正式英语常避免缩写，偏好更明确、抽象、结构化表达。
- 短语动词通常比单词替代更不正式：put off vs postpone。
- 直接程度也影响语域：Can you send it? vs Could you please send it at your earliest convenience?
- 选择要匹配场景，而不是盲目追求“更高级”。
例句
- It is essential that all data be reviewed. (formal) - 必须审查所有数据。（正式）
- It's really important that we check everything. (neutral) - 我们把一切都检查一遍真的很重要。（中性）
- We need to sort out the problem. (informal) - 我们得把这个问题处理好。（口语）
- We need to resolve the issue. (formal) - 我们需要解决该问题。（正式）
- I would be grateful if you could respond by Friday. (formal) - 如您能在周五前回复，我将不胜感激。（正式）
常见错误
- ❌ I would be grateful if you can reply soon. -> ✅ I would be grateful if you could reply soon.
- ❌ We need to sort out this matter immediately. (in a very formal report) -> ✅ We need to resolve this matter immediately.
- ❌ It is essential that everyone is present. -> ✅ It is essential that everyone be present. / ✅ It is essential that everyone should be present.