给定一个英文段落，将其中所有的单词首字母大写（即句子中的每个单词都要以大写字母开头）并返回修改后的段落。
this is a paragraph about artificial intelligence. it is essential for developing intelligent machines that can work and think like humans.
This Is A Paragraph About Artificial Intelligence. It Is Essential For Developing Intelligent Machines That Can Work And Think Like Humans.