python有几种循环遍历的方法？

words = ['cat', 'window', 'defenestrate']

for w in words:

    print(w, len(w))

# 使用数组访问操作符，能够迅速地生成数组的副本

for w in words[:]:

    if len(w) > 6:

        words.insert(0, w)

# words -> ['defenestrate', 'cat', 'window', 'defenestrate']

a = ['Mary', 'had', 'a', 'little', 'lamb']

for i in range(len(a)):

    print(i, a[i])