<p>在 is &quot;at...something is happening&quot;; 当 is &quot;when...something is happening&quot;. Sometimes they are interchangeable, but not always.</p>
<p>&quot;在我&quot;讲话的时候, ... = &quot;当我&quot;讲话的时候, ... The two sentences are interchangeable.</p>
<p>But 如果&quot;在我&quot;讲话的时候... (If at the time I am talking, ...) and 如果&quot;当我&quot;讲话的时候... (If when I am talking, ...) are not, because &quot;if&quot; conflicts with &quot;when&quot; - &quot;if&quot; indicates uncertain about something, but &quot;when&quot; indicates certainty.</p>
<p><strong>Usual patterns of 在 and 当:</strong></p>
<ul>
<li><p>我觉得<strong>在</strong>我给你发了修改的文章<strong>後</strong>说会更好一点。[Pattern: 在...(之)後]</p>
</li>
<li><p>我觉得<strong>当</strong>我给你发了修改的文章<strong>时</strong>说会更好一点。[Pattern: 当...(之)时]</p>
</li>
</ul>
<p><strong>Comments on the example sentences:</strong></p>
<ul>
<li><p>当我<strong>说</strong>中文<strong>时</strong>, 很搞笑. (When I speak Chinese, it sounds funny.)</p>
</li>
<li><p>在我说中文时…… does not match the usual pattern 在...之前/後/間. But, 在我演說时…… = 当我演說时……, because 演說时 is a complete phrase by itself, that does not fall within the usual patterns.</p>
</li>
<li><p>当他去中国旅行时…… = 在他去中国旅行时…… Same as above, 旅行时 is a complete phrase by itself.</p>
</li>
<li><p>当下雨时我用雨伞。= 在下雨时我用雨伞。下雨时 is a complete phrase by itself.</p>
</li>
</ul>

CC BY-SA 4.0
2021-12-12T16:16:23.123Z
May I ask for some clarification regarding: ”演說时 is a complete phrase by itself“ And by extension, if I want to use 在……时，then it must be a complete phrase by itself?
MuchAppreciated25
CC BY-SA 4.0
2021-12-12T17:27:41.440Z
I don't quite understand what you mean.  But look at the pattern - 演說, 旅行, and 下雨 all are actions (verb) that differ from 中文, a noun, 中文时 can't be a standalone phrase.
r13
CC BY-SA 4.0
2021-12-11T23:37:37.543Z
2021-12-11T23:37:37.543Z
r13
<p>I always see 在……时/的时候，but whenever I try to use this phrase, natives tell me to say 当……时/的时候 instead. Examples of 在……时/的时候 from natives：</p>
<blockquote>
<p>如果我<code>在</code>讲话<code>的时候</code>用到这些词的话……</p>
<p><code>在</code>阅读某些文章<code>的时候</code>……</p>
<p>我觉得<code>在</code>我给你发了修改的文章<code>时</code>说会更好一点。</p>
<p><code>在</code>上班<code>时</code>……</p>
<p><code>在</code>课堂<code>时</code>……</p>
</blockquote>
<p>我自己造句的：</p>
<blockquote>
<p>当我说中文时……（在我说中文时……？）</p>
<p>当他去中国旅行时……（在他去中国旅行时……？）</p>
<p>当下雨时我用雨伞。（在下雨时我用雨伞 ？）</p>
</blockquote>
<p>Just wondering if anyone can shed some light on this. When is it more preferable to use one over the other?</p>

<grammar><usage><sentence-structure>
When is it okay to say 在……的时候 instead of 当……的时候？
# When is it okay to say 在……的时候 instead of 当……的时候？

(Asked by: username_0 on 2021-12-11)

I always see 在……时/的时候，but whenever I try to use this phrase, natives tell me to say 当……时/的时候 instead. Examples of 在……时/的时候 from natives：

> 如果我`在`讲话`的时候`用到这些词的话……
>
> `在`阅读某些文章`的时候`……
>
> 我觉得`在`我给你发了修改的文章`时`说会更好一点。
>
> `在`上班`时`……
>
> `在`课堂`时`……

我自己造句的：

> 当我说中文时……（在我说中文时……？）
>
> 当他去中国旅行时……（在他去中国旅行时……？）
>
> 当下雨时我用雨伞。（在下雨时我用雨伞 ？）

Just wondering if anyone can shed some light on this. When is it more preferable to use one over the other?

**Tags:** grammar, usage, sentence-structure


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## 1 answers

### Answer by username_1 on 2021-12-11. Score: 1 | Accepted answer

在 is "at...something is happening"; 当 is "when...something is happening". Sometimes they are interchangeable, but not always.

"在我"讲话的时候, ... = "当我"讲话的时候, ... The two sentences are interchangeable.

But 如果"在我"讲话的时候... (If at the time I am talking, ...) and 如果"当我"讲话的时候... (If when I am talking, ...) are not, because "if" conflicts with "when" - "if" indicates uncertain about something, but "when" indicates certainty.

**Usual patterns of 在 and 当:**

* 我觉得**在**我给你发了修改的文章**後**说会更好一点。[Pattern: 在...(之)後]
* 我觉得**当**我给你发了修改的文章**时**说会更好一点。[Pattern: 当...(之)时]

**Comments on the example sentences:**

* 当我**说**中文**时**, 很搞笑. (When I speak Chinese, it sounds funny.)
* 在我说中文时…… does not match the usual pattern 在...之前/後/間. But, 在我演說时…… = 当我演說时……, because 演說时 is a complete phrase by itself, that does not fall within the usual patterns.
* 当他去中国旅行时…… = 在他去中国旅行时…… Same as above, 旅行时 is a complete phrase by itself.
* 当下雨时我用雨伞。= 在下雨时我用雨伞。下雨时 is a complete phrase by itself.

> **Comments:**
> **username_0**: May I ask for some clarification regarding: ”演說时 is a complete phrase by itself“ And by extension, if I want to use 在……时，then it must be a complete phrase by itself?  
> **username_1**: I don't quite understand what you mean.  But look at the pattern - 演說, 旅行, and 下雨 all are actions (verb) that differ from 中文, a noun, 中文时 can't be a standalone phrase.  

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