<p>Depend on what the emphasis is, there are quite a few idioms you can use in this context. </p>

<p>Some suggestion: </p>

<p>判若兩人 (like a different person)</p>

<p>前後判若兩人 (like a different person from before)</p>

<p>大起大落 (up and down to the extreme/ high and low to the extreme)</p>

<p>峰迴路轉 (surprising, unexpected)</p>

<p>前後反覆 (change completely from before/ turn 180 degree)</p>

<p>一百八十度轉變 (turn 180 degree)</p>

<p><em>If you are looking for an idiom 前後判若兩人 fit in this context the best, but 一百八十度轉變 itself is a common phrase</em></p>

CC BY-SA 4.0
2020-02-14T04:39:13.207Z
前後判若兩人 seems to fit perfectly.  Thanks.  (I'm trying to "show, don't tell" her volatility to the reader, so I'm avoiding words meaning 反覆 which spoils the story, even though they're correct.)
Becky 李蓓
CC BY-SA 4.0
2020-02-13T13:06:51.857Z
2020-02-13T13:12:03.000Z
2020-02-13T13:12:03.000Z
Tang Ho
<p>To add to the collection:
反复无常：Changed unpredictably to something that is in an opposite direction.</p>

<p>e.g. The weather can go from one extreme to the other.  == The weather can go 反复无常</p>

CC BY-SA 4.0
2020-02-15T12:00:05.190Z
2020-02-15T12:00:05.190Z
jazelly
<p>忽喜忽忧 is probably what you need.  It means 
时而欢喜，时而忧伤。</p>

<p>For example:</p>

<blockquote>
  <p>投资人的心情随着股价涨跌，忽喜忽忧，变化莫测。<br>
  <sub><a href="http://www.cihai123.com/cidian/1211886.html" rel="nofollow noreferrer">CiHai123.com</a></sub></p>
</blockquote>

CC BY-SA 4.0
2020-02-14T04:42:27.690Z
[`"忽喜忽忧"`](https://www.baidu.com/s?word="忽喜忽忧") has very few Baidu hits---I've never gotten anything past my teacher without millions of hits.
Becky 李蓓
CC BY-SA 4.0
2020-02-14T07:39:52.343Z
@Becky李蓓 忽... 忽...  is probably a common structure.  E. g.  忽慢忽快，忽悲忽喜，忽上忽下，etc.  What I quoted in my answer was actually from a dictionary.
dan
CC BY-SA 4.0
2020-02-14T09:21:08.677Z
@Becky李蓓 here is a link: http://www.cihai123.com/cidian/1211886.html
dan
CC BY-SA 4.0
2020-02-14T09:23:37.987Z
@Becky李蓓 A caveat: the way you use it is crucial.  It could sound weird when you put it in a wrong way.
dan
CC BY-SA 4.0
2020-02-13T13:20:18.253Z
2020-02-14T09:33:02.930Z
2020-02-14T09:33:02.930Z
dan
<p>In my story, 孔琳's behavior has changed from ultra-depressed to ultra-optimistic in a matter of moments (she has an unstable personality).  Her friends (陈叶 and 胡灵阳) are staring at her in amazement, and I want to write...</p>

<blockquote>
  <p>现在陈叶和胡灵阳在一起站着，惊喜地盯着孔琳[chengyu]的变化。</p>
</blockquote>

<p>I want to describe this change using a chengyu, but the closest I found was <a href="https://baike.baidu.com/item/%E4%BB%A5%E8%80%B3%E4%BB%A3%E7%9B%AE" rel="nofollow noreferrer">以耳代目</a> and <a href="https://baike.baidu.com/item/%E4%BB%A5%E8%80%B3%E4%B8%BA%E7%9B%AE" rel="nofollow noreferrer">以耳为目</a> which are variants.  It's not bad (it means something like "substitute ears for eyes"), but I don't think it works grammatically above.  I'm also unsure that the context works here; perhaps it refers to blind people.</p>

<p><strong>Question</strong>: How do I use a chengyu (idiom) to describe a "one extreme to the other" kind of transformation?</p>

<hr>

<p>English derived from above Chinese; only to be used "in case of emergency" (i.e., if the Chinese is incomprehensible):</p>

<blockquote class="spoiler">
  <p> <sub><sup>Now Chen Ye and Hu Lingyang [are] standing, surprisedly staring [at] Kong Lin's from-one-extreme-to-the-other change.</sup></sub></p>
</blockquote>

CC BY-SA 4.0
2020-02-13T13:16:36.063Z
Base on the links you posted, neither 以耳代目 nor 以耳为目would work here.
fefe
CC BY-SA 4.0
2020-02-13T19:23:32.383Z
aha, first word comes to mind was ```破涕为笑```
Shaw
CC BY-SA 4.0
2020-02-16T22:55:50.767Z
Hi 李蓓, I am not sure whether I misunderstand what you want to express, I think you can't use 盯着（adj.）的变化。
BING
<chengyu>
How do I use a chengyu (idiom) to describe a "one extreme to the other" kind of transformation?
# How do I use a chengyu (idiom) to describe a "one extreme to the other" kind of transformation?

(Asked by: username_0 on 2020-02-13)

In my story, 孔琳's behavior has changed from ultra-depressed to ultra-optimistic in a matter of moments (she has an unstable personality). Her friends (陈叶 and 胡灵阳) are staring at her in amazement, and I want to write...

> 现在陈叶和胡灵阳在一起站着，惊喜地盯着孔琳[chengyu]的变化。

I want to describe this change using a chengyu, but the closest I found was [以耳代目](https://baike.baidu.com/item/%E4%BB%A5%E8%80%B3%E4%BB%A3%E7%9B%AE) and [以耳为目](https://baike.baidu.com/item/%E4%BB%A5%E8%80%B3%E4%B8%BA%E7%9B%AE) which are variants. It's not bad (it means something like "substitute ears for eyes"), but I don't think it works grammatically above. I'm also unsure that the context works here; perhaps it refers to blind people.

**Question**: How do I use a chengyu (idiom) to describe a "one extreme to the other" kind of transformation?

---

English derived from above Chinese; only to be used "in case of emergency" (i.e., if the Chinese is incomprehensible):

> Now Chen Ye and Hu Lingyang [are] standing, surprisedly staring [at] Kong Lin's from-one-extreme-to-the-other change.

**Tags:** chengyu
> **Comments:**
> **username_1**: Base on the links you posted, neither 以耳代目 nor 以耳为目would work here.  
> **username_2**: aha, first word comes to mind was ```破涕为笑```  
> **username_3**: Hi 李蓓, I am not sure whether I misunderstand what you want to express, I think you can't use 盯着（adj.）的变化。  

---

## 3 answers

### Answer by username_4 on 2020-02-13. Score: 1 | Accepted answer

Depend on what the emphasis is, there are quite a few idioms you can use in this context.

Some suggestion:

判若兩人 (like a different person)

前後判若兩人 (like a different person from before)

大起大落 (up and down to the extreme/ high and low to the extreme)

峰迴路轉 (surprising, unexpected)

前後反覆 (change completely from before/ turn 180 degree)

一百八十度轉變 (turn 180 degree)

*If you are looking for an idiom 前後判若兩人 fit in this context the best, but 一百八十度轉變 itself is a common phrase*

> **Comments:**
> **username_0**: 前後判若兩人 seems to fit perfectly.  Thanks.  (I'm trying to "show, don't tell" her volatility to the reader, so I'm avoiding words meaning 反覆 which spoils the story, even though they're correct.)  

---

### Answer by username_5 on 2020-02-15. Score: 1

To add to the collection:
反复无常：Changed unpredictably to something that is in an opposite direction.

e.g. The weather can go from one extreme to the other. == The weather can go 反复无常


---

### Answer by username_6 on 2020-02-13. Score: 1

忽喜忽忧 is probably what you need. It means
时而欢喜，时而忧伤。

For example:

> 投资人的心情随着股价涨跌，忽喜忽忧，变化莫测。  
> [CiHai123.com](http://www.cihai123.com/cidian/1211886.html)

> **Comments:**
> **username_0**: [`"忽喜忽忧"`](https://www.baidu.com/s?word="忽喜忽忧") has very few Baidu hits---I've never gotten anything past my teacher without millions of hits.  
> **username_6**: @Becky李蓓 忽... 忽...  is probably a common structure.  E. g.  忽慢忽快，忽悲忽喜，忽上忽下，etc.  What I quoted in my answer was actually from a dictionary.  
> **username_6**: @Becky李蓓 here is a link: http://www.cihai123.com/cidian/1211886.html  
> **username_6**: @Becky李蓓 A caveat: the way you use it is crucial.  It could sound weird when you put it in a wrong way.  

---

