老师，我了解到不定冠词a和复数都可以表示泛指，a和复数是否是any的意思？ 

还有我看有些书把泛指表示all的意思。 all 和 any 是一个意思吗？

give me a pen (any pen?) 

He is a teacher(any teacher?)

He works in a factory(any factory?)

People are better educated now （any people？all people?）

People flocked to hear him speak. （any people? all people）

I don't have children (any children, all children)