擅长:python、mysql、java
<p>你的正则表达式是</p>
<pre><code>\bfire\b(?!.*\bcrews\b)
</code></pre>
<p><a href="http://regex101.com/r/jH6qM3/1" rel="nofollow">DEMO</a></p>
<p>如果你想打印整行的话你的正则表达式应该是</p>
<pre><code>.*\bfire\b(?!.*\bcrews\b).*
</code></pre>
<p>Python代码</p>
<pre><code>>>> import re
>>> data = """car is on fire
... found fire crews on scene"""
>>> m = re.search(r'\bfire\b(?!.*\bcrews\b)', data, re.M)
>>> m.group()
'fire'
>>> m = re.search(r'.*\bfire\b(?!.*\bcrews\b).*', data, re.M)
>>> m.group()
'car is on fire'
</code></pre>