Phrase
that is
phrase
即；也就是说
used to introduce a more precise or clearer explanation of what has just been said
作插入语，相当于“也就是说”，常缩略为 i.e.
(作插入语)那就是
In use
We'll meet at the station, that is, in front of the main entrance.
She prefers simple meals, that is, dishes with only a few ingredients.
You need to finish the report by Friday, that is, before the weekend.
A, that is, B
用于对前文A进行解释或重新表述，B是更具体或更简单的说法。
He is a linguist, that is, a person who studies language.
他是一位语言学家，那就是，研究语言的人。
That is, [sentence].
用于句首引出对前文或整个语境的解释。
That is, we need to revise the plan.
那就是，我们需要修改计划。
Common mistakes
He is a teacher, that is he teaches English.He is a teacher, that is, he teaches English.
英语中，作插入语的'that is'前后需用逗号隔开，表示对前文的解释说明。中文里“那就是”不要求逗号，导致学习者遗漏逗号，造成句子结构混乱。
I enjoy outdoor activities, that is, hiking and camping.I enjoy outdoor activities, for example, hiking and camping.
'that is'用于重新表述或澄清前文，而非列举例子。中文“那就是”有时被误用于举例，但英语中列举例子应使用'for example'或'such as'。
Connections
Confusing words
- namely
- 即 · namely 用于具体列举，而 that is 用于解释或重述
- i.e.
- 即 · i.e. 是拉丁文缩写，通常用于书面语，与 that is 同义，但更正式
- in other words
- 换句话说 · in other words 用于换种方式表达，而 that is 更直接引出解释
Learner notes
Grammar Note
作插入语，引出对前文的解释或说明；通常在句中用逗号隔开。
Dictionary facts from DICTIONARY_API_DEV, ECDICT, WIKTIONARY.