<p><strong>Usually you can use any of them, but &quot;攻其无备，出其不意&quot; is the best one.</strong></p>
<p>The reason is this word is from 《孙子兵法》, an ancient military book by a famous military strategist Sun Wu(孙武), and it is &quot;攻其无备，出其不意&quot; originally in that book.</p>
<p>Also, in 《现代汉语词典》（第7版）, there is &quot;攻其无备，出其不意&quot; under &quot;出其不意&quot; as an example.</p>

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2021-02-16T17:11:03.017Z
Art of War, a very famous book :)
Soroush
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2021-02-16T14:39:21.143Z
2021-02-16T14:39:21.143Z
T-Pioneer
<p>Could you please let me know which of these sound right and why the other ones sound wrong? I'm not sure about the difference between 不 and 无.</p>
<p>出其不意，攻其不备</p>
<p>攻其不备，出其不意</p>
<p>攻其无备，出其无意</p>
<p>攻其不备，出其无意</p>
<p>攻其无备，出其不意</p>
<p><strong>都可以用吗</strong></p>

<difference><idioms><synonyms><chengyu>
Attack them when they are unready, take them by surprise ： 这个成语有多少方法可以说？
# Attack them when they are unready, take them by surprise ： 这个成语有多少方法可以说？

(Asked by: username_0 on 2021-02-16)

Could you please let me know which of these sound right and why the other ones sound wrong? I'm not sure about the difference between 不 and 无.

出其不意，攻其不备

攻其不备，出其不意

攻其无备，出其无意

攻其不备，出其无意

攻其无备，出其不意

**都可以用吗**

**Tags:** difference, idioms, synonyms, chengyu

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## 1 answers

### Answer by username_1 on 2021-02-16. Score: 1 | Accepted answer

**Usually you can use any of them, but "攻其无备，出其不意" is the best one.**

The reason is this word is from 《孙子兵法》, an ancient military book by a famous military strategist Sun Wu(孙武), and it is "攻其无备，出其不意" originally in that book.

Also, in 《现代汉语词典》（第7版）, there is "攻其无备，出其不意" under "出其不意" as an example.

> **Comments:**
> **username_0**: Art of War, a very famous book :)  

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