首先，我们需要定义一个函数来计算句子的长度：

def sentence_length(sentence): return len(sentence.strip())

然后，我们可以使用sorted函数，将句子列表按照长度进行排序：

sentences = ["This is a short sentence.", "This is a much longer sentence that is used for testing purposes.", "This is an even longer sentence that is more testing."] sorted_sentences = sorted(sentences, key=sentence_length)

最后，我们可以打印排好序的句子列表：

print(sorted_sentences)

输出结果如下：

['This is a short sentence.', 'This is an even longer sentence that is more testing.', 'This is a much longer sentence that is used for testing purposes.']