import re

 patt = '[A-Za-z]+ [A-Za-z]+'  # 方法一 +加号操作符匹配它左边的正则表达式至少出现一次的情况

 # patt = '[A-Za-z]+[ A-Za-z]+'  # 方法二
 5 # patt = '[A-Za-z]+\s[A-Za-z]+' # 方法三   \s匹配空白 

 name1 = 'zhang san'

 name2 = 'li si'

 name3 = 'wang ermazi'

 m = re.match(patt, name1)

 m1 = re.match(patt, name2)

 m2 = re.match(patt, name3)

 if m is not None:

     print(m.group())

 if m is not None:

     print(m1.group())

 if m is not None:

     print(m2.group())