for all the people of the world

for all the people of the world.
因为all the people是在【限定范围 of the world】,是【特指】,所以要定冠词the.
因为the world是【独一无二的】,又是【固定用法】,所以是the world.
再问： 谢谢你，我还想问一下在一个句子里的another one与直接说another+你要指的东西的单数，有什么区别?
再答： another one与直接说another+你要指的东西的单数，应该没有区别。如：
I have three daughters. One is a nurse, another (one/ daughter) is a teacher and another (one/ daughter) is a worker.