classmates = ('Tom','Jerry','Dominic')
print('classmates = ',classmates)
print('len(classmates)',len(classmates))
print('classmates[0]',classmates[0])
print('classmates[1]',classmates[1])
print('classmates[2]',classmates[2])

#执行结果是Dominic
print('classmates[-1]',classmates[-1])    

#can not modify tuple()元组的意思
#classmates[0] = "abc"

