1、list[0]与list[0:1]

前者返回一个值，后者是列表

a = [2, 0, 6]
a[0]                   # 2
a[0:1]                 # [2]

2、b = a[:]与b = a

前者产生一个新列表，与原列表之后是否修改无关，a、b是两个列表
后者只是为原列表加了个标签，a、b都是一个列表

a = [0,6,2,5,7,4,9,3]
b = a[:]
c = a
print('b',b)                # b [0, 6, 2, 5, 7, 4, 9, 3] 
print('c',c)                # c [0, 6, 2, 5, 7, 4, 9, 3] 
a.sort()                    
print('a',a)                # a [0, 2, 3, 4, 5, 6, 7, 9]
print('b',b)                # b [0, 6, 2, 5, 7, 4, 9, 3]
print('c',c)                # c [0, 2, 3, 4, 5, 6, 7, 9]

a = [1,4,2,5]
b = a
a = [2]
print(b)                     # b [1,4,2,5]

3、获取列表元素

a = ['1.a一','2.b二','3.c三']
a[0]                          # 1.a一
a[0][1]                       # .