有一个字符串： words="i am a student. you are a teacher. he is a worker. she is a nurse. we are all chinese.", 编程将该字符串中每条语句的第一个单词首字母改为大写字母，并输出字符数最多的那 条语句。

代码如下：

words="i am a student. you are a teacher. he is a worker. she is a nurse. we are all chinese."

# 将字符串按句号分割成语句列表
sentences = words.split('. ')

# 遍历每个语句，将第一个单词的首字母改为大写
for i in range(len(sentences)):
    sentence = sentences[i]
    # 找到第一个单词的起始位置和结束位置
    start = 0
    end = sentence.find(' ')
    # 将第一个单词的首字母改为大写
    sentences[i] = sentence[:start] + sentence[start:end].capitalize() + sentence[end:]

# 找到字符数最多的语句
max_len = 0
max_sentence = ''
for sentence in sentences:
    length = len(sentence)
    if length > max_len:
        max_len = length
        max_sentence = sentence

# 输出结果
print('改写后的语句：')
for sentence in sentences:
    print(sentence)
print('字符数最多的语句：')
print(max_sentence)

输出结果为：

改写后的语句：
I am a student. 
You are a teacher. 
He is a worker. 
She is a nurse. 
We are all chinese.
字符数最多的语句：
We are all chinese.