3-1 姓名： 将一些朋友的姓名存储在一个列表中，并将其命名为names 。依次访问该列表中的每个元素，从而将每个朋友的姓名都打印出来。
names = ['ada', 'eric', 'per']
print(names[0])
print(names[1])
print(names[2])
3-2 问候语： 继续使用练习3-1中的列表，但不打印每个朋友的姓名，而为每人打印一条消息。每条消息都包含相同的问候语，但抬头为相应朋友的姓名。
names = ['ada', 'eric', 'per']
print(names[0].title() + " good moring.")
print(names[1].title() + " good moring.")
print(names[2].title() + " good moring.")
3-3 自己的列表： 想想你喜欢的通勤方式，如骑摩托车或开汽车，并创建一个包含多种通勤方式的列表。根据该列表打印一系列有关这些通勤方式的宣言，如“I would like to own a Honda motorcycle”。
ways = ['car', 'subway', 'motorcycle']
print("I would like to buy a BMW " + ways[0] + ".")
print("I would like to buy a " + ways[1] + ".")
print("I would like to buy a Honda " + ways[2] + ".")
3-4 嘉宾名单 ：如果你可以邀请任何人一起共进晚餐（无论是在世的还是故去的），你会邀请哪些人？请创建一个列表，其中包含至少3个你想邀请的人；然后，使用这个列表打印消息，邀请这些人来与你共进晚餐。
names = ['ada', 'eric', 'per']
print(names[0].title() + " would you like to have dinner with me?")
print(names[1].title() + " would you like to have dinner with me?")
print(names[2].title() + " would you like to have dinner with me?")
3-5 修改嘉宾名单 ：你刚得知有位嘉宾无法赴约，因此需要另外邀请一位嘉宾。
以完成练习3-4时编写的程序为基础，在程序末尾添加一条print 语句，指出哪位嘉宾无法赴约。
print(names[2].title() + " can not come")
修改嘉宾名单，将无法赴约的嘉宾的姓名替换为新邀请的嘉宾的姓名。
names[2] = 'unio'
再次打印一系列消息，向名单中的每位嘉宾发出邀请。
print(names[0].title() + " would you like to have dinner with me?")
print(names[1].title() + " would you like to have dinner with me?")
print(names[2].title() + " would you like to have dinner with me?")
3-6 添加嘉宾 ：你刚找到了一个更大的餐桌，可容纳更多的嘉宾。请想想你还想邀请哪三位嘉宾。
以完成练习3-4或练习3-5时编写的程序为基础，在程序末尾添加一条print 语句，指出你找到了一个更大的餐桌。
print('I find a bigger table.')
使用insert() 将一位新嘉宾添加到名单开头。
names.insert(0, 'anni')
使用insert() 将另一位新嘉宾添加到名单中间。
names.insert(2, 'geri')
使用append() 将最后一位新嘉宾添加到名单末尾。
names.append('nazi')
打印一系列消息，向名单中的每位嘉宾发出邀请。
print(names[0].title() + " would you like to have dinner with me?")
print(names[1].title() + " would you like to have dinner with me?")
print(names[2].title() + " would you like to have dinner with me?")
print(names[3].title() + " would you like to have dinner with me?")
print(names[4].title() + " would you like to have dinner with me?")
print(names[5].title() + " would you like to have dinner with me?")
3-7 缩减名单 ：你刚得知新购买的餐桌无法及时送达，因此只能邀请两位嘉宾。
以完成练习3-6时编写的程序为基础，在程序末尾添加一行代码，打印一条你只能邀请两位嘉宾共进晚餐的消息。
print('The table can not arrive on time, so just two people can have dinner.')
使用pop() 不断地删除名单中的嘉宾，直到只有两位嘉宾为止。每次从名单中弹出一位嘉宾时，都打印一条消息，让该嘉宾知悉你很抱歉，无法邀请他来共进晚餐。
n1 = names.pop()
print(n1 + " sorry to tell you can not have dinner with me.")
n2 = names.pop()
print(n2 + " sorry to tell you can not have dinner with me.")
n3 = names.pop()
print(n3 + " sorry to tell you can not have dinner with me.")
n4 = names.pop()
print(n4 + " sorry to tell you can not have dinner with me.")
对于余下的两位嘉宾中的每一位，都打印一条消息，指出他依然在受邀人之列。
print(names[0] + ", welcome to have dinner.")
print(names[1] + ", welcome to have dinner.")
使用del 将最后两位嘉宾从名单中删除，让名单变成空的。打印该名单，核实程序结束时名单确实是空的。
del names[0]
del names[0]
print(names)