如何在.txt文件中一组下一行单词中的点后下一行

我的代码有问题。我有一个文本文件，并且在此文本文件中是一千个来自句子的带标签的/下一行的单词。我的问题是我想还原此文本文件中的单词，然后再次使其成为句子。

我想过一种制作for循环语句的方法，如果命中点.，它将在列表中存储该语句。

with('test','r') as f:
    text = f.open()

sentence = []
sentences = []
for words in text:
    if words != "."
       sentence.append(words)
    elif words == "."
       sentence.append(words)
       sentences.append(sentence)
       sentence = []

#Sample output
#[['This', 'is', 'a', 'sentence', '.'], ['This', 'is', 'the', 'second', 'sentence', '.'],
#['This', 'is', 'the', 'third', 'sentence', '.']], 

#This is the text file
This
is
a
sentence
.
This
is
the
second
sentence
.
This
is
thr
third
sentence
.

代码还可以，但是有点复杂。我发现了一个简短而又不太复杂的主意。先感谢您。