1、实例: 下载一首英文的歌词或文章，将所有,.？！等替换为空格，将所有大写转换为小写，统计某几个单词出现的次数，分隔出一个一个的单词。
s='''You were the shadow to my light
Did you feel us?
Another star
You fade away
Afraid our aim is out of sight
Wanna see us
Alive
Where are you now?
Where are you now?
Where are you now?
Was it all in my fantasy?
Where are you now?
Were you only imaginary?
Where are you now?
Atlantis
Under the sea
Under the sea
Where are you now?
Another dream
The monster's running wild inside of me
I'm faded
I'm faded
So lost, I'm faded
I'm faded
So lost, I'm faded
These shallow waters never met what I needed
I'm letting go a deeper dive
Eternal silence of the sea. I'm breathing alive
Where are you now?
Where are you now?
Under the bright but faded lights
You've set my heart on fire
Where are you now?
Where are you now?
Where are you now?
Atlantis
Under the sea
Under the sea
Where are you now?
Another dream
The monster's running wild inside of me
I'm faded
I'm faded
So lost, I'm faded
I'm faded
So lost, I'm faded
'''
s=s.lower()
for i in',.?!':
s=s.replace(i,' ')
words=s.split(' ')
print(s)
print ('fade:{0}'.format(s.count('fade')))
print ('faded:{0}'.format(s.count('faded')))
print ('where are you now :{0}'.format(s.count('where are you now ')))
2、列表实例：由字符串创建一个作业评分列表，做增删改查询统计遍历操作。例如，查询第一个3分的下标，统计1分的同学有多少个，3分的同学有多少个等。
3、简要描述列表与元组的异同。
元组用方括号[]赋值，用逗号隔开每一个元素，列表中的元素可以增删查改，还能改变元素的类型，元组用小括号（）赋值，元组内的元素可供读取，但无法修改。