正則的疑惑，總是抓不到！

>>> str='''<td>
...                                 
...                                     
...                                     
...                                         607
...                                     
...                                 
...                             </td>
...                             <td>
...                                 
...                                     
...                                     
...                                         13
...                                     
...                                 
...                             </td>
...                             <td>
...                                 
...                                     
...                                     
...                                         2.14%
...                                     
...                                 
...                             </td>
...                             <td>
...                                 
...                                     
...                                     
...                                         6.78
...                                     
...                                 
...                             </td>
...                             <td>
...                                 
...                                     
...                                     500
...                                 
...                             </td>
...                             <td>
...                                 
...                                     
...                                     
...                                         0.52
...                                     
...                                 
...                             </td>'''
>>> s2=re.search('<td>(.*?)</td>\s*<td>*?</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>.*?</td>',str)
>>> s2.group(1)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'
>>> s2=re.search('<td>(.*?)</td>\s*<td>*?</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>.*?</td>',str,re.S)
>>> s2
>>> s2=re.search('<td>(.*?)</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>(.*?)</td>\s*<td>>*?</td>\s*<td>(.*?)</td>',str,re.S)
>>> s2
>>> s2=re.search(u'<td>(.*?)</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>(.*?)</td>\s*<td>>*?</td>\s*<td>(.*?)</td>',str,re.S)
>>> s2
>>> s2=re.search('<td>(.*?)</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>>*?</td>\s*<td>.*?</td>',str,re.S)
>>> s2
>>> s2=re.search('<td>(.*?)</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>.*?</td>\s*<td>*?</td>\s*<td>.*?</td>',str,re.S)
>>> s2
>>> s2

這個(gè)我明明寫(xiě)正確的，為啥匹配不到請(qǐng)高手指點(diǎn)，謝謝！

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