1. tuples:
(3) -> 3 but (3,) indicates a tuple -> (3,)
2. tuples and lists:
tuples:num = (1,2,3) (3,) 不可修改 num(1) = 4 -> ‘error‘
lists:num = [1,2,3] [3] 可以修改 num[1] = 4 -> [1,4,3]
.
## universities
Techs = [‘MIT‘, ‘Cal Tech‘]
Ivys = [‘Harvard‘, ‘Yale‘, ‘Brown‘]
Univs = [Techs, Ivys]
Univs1 = [[‘MIT‘, ‘Cal Tech‘], [‘Harvard‘, ‘Yale‘, ‘Brown‘]]
Techs.append(‘RPI‘)
print(‘Univs = ‘)
print(Univs)
print(‘‘)
print(‘Univs1 =‘)
print(Univs1)
for e in Univs:
print(‘Univs contains ‘)
print(e)
print(‘ which contains‘)
for u in e:
print(‘ ‘ + u)
原文：http://www.cnblogs.com/njuzwr/p/4507478.html