Python正则表达式 r'(.*) are (.*?) .*'的深入理解

#!/usr/bin/python3
import re
 
line = "Cats are smarter than dogs"
# .* 表示任意匹配除换行符（\n、\r）之外的任何单个或多个字符
# (.*?) 表示"非贪婪"模式，只保存第一个匹配到的子串
matchObj = re.match( r'(.*) are (.*?) .*', line, re.M|re.I)
 
if matchObj:
   print ("matchObj.group() : ", matchObj.group())
   print ("matchObj.group(1) : ", matchObj.group(1))
   print ("matchObj.group(2) : ", matchObj.group(2))
else:
   print ("No match!!")

  #!/usr/bin/Python3
  
  import re
   
  #line = "Cats are smarter than dogs"
  line = "a a Cats are Cats are smarter than dogs"
  # .* 表示任意匹配除换行符（\n、\r）之外的任何单个或多个字符
  # (.*?) 表示"非贪婪"模式，只保存第一个匹配到的子串
  matchObj = re.match( r'(.*) are (.*) .*', line, re.M|re.I)
   
  if matchObj:
      print ("matchObj.group() : ", matchObj.group())
      print ("matchObj.group(1) : ", matchObj.group(1))
      print ("matchObj.group(2) : ", matchObj.group(2))
  else:                                                                      
      print ("No match!!")

 #!/usr/bin/python3
  
  import re
   
  #line = "Cats are smarter than dogs"
  line = "a a Cats are Cats are smarter than dogs"
  # .* 表示任意匹配除换行符（\n、\r）之外的任何单个或多个字符
  # (.*?) 表示"非贪婪"模式，只保存第一个匹配到的子串
  matchObj = re.match( r'(.*?) are (.*) .* .*', line, re.M|re.I)             
   
  if matchObj:
      print ("matchObj.group() : ", matchObj.group())
      print ("matchObj.group(1) : ", matchObj.group(1))
      print ("matchObj.group(2) : ", matchObj.group(2))
  else:
      print ("No match!!")

  #!/usr/bin/python3
  
  import re
  
  #line = "Cats are smarter than dogs"
  line = "a a Cats are CatsB are smarter are than are dogs are dogs b c d e"
  # .* 表示任意匹配除换行符（\n、\r）之外的任何单个或多个字符
  # (.*?) 表示"非贪婪"模式，只保存第一个匹配到的子串
  matchObj = re.match( r'(.*?) are (.*?) (.*?) (.*) .*', line, re.M|re.I)    
   
  if matchObj:
      print ("matchObj.group() : ", matchObj.group())
      print ("matchObj.group(1) : ", matchObj.group(1))
      print ("matchObj.group(2) : ", matchObj.group(2))
      print ("matchObj.group(3) : ", matchObj.group(3))
      print ("matchObj.group(4) : ", matchObj.group(4))
  else:
      print ("No match!!")