这意味着从函数中提取列表/元组中的第一项。
In [1]: "this is a long sentence".split()Out[1]: ['this', 'is', 'a', 'long', 'sentence']In [2]: "this is a long sentence".split()[0]Out[2]: 'this'

这意味着从函数中提取列表/元组中的第一项。
In [1]: "this is a long sentence".split()Out[1]: ['this', 'is', 'a', 'long', 'sentence']In [2]: "this is a long sentence".split()[0]Out[2]: 'this'