第三次

str='''Baby, baby, baby nooo 
My baby, baby, baby noo 
My baby, baby, baby nooo 
I thought youd always be mine mine 
Baby, baby, baby nooo 
My baby, baby, baby noo 
My baby, baby, baby nooo'''
print(str);

print(str.lower());

print(str.split())

print("统计每个单词出现的次数为:")
strSet=set(str.split())
for word in strSet:
   print(word,str.split().count(word))