pron.

1. 某人，有人
   Are you expecting someone this afternoon?

   今天下午你是不是等什么人？

   Someone left this for you.

   有人把这留给你。

n.

1. 重要人物，有名气的人
   If you had studied harder, you might have become someone.

   如果你当初学习努力的话，你或许已经成了重要人物了。

pron.

1. an unknown or unspecified person.
2. a person of importance or authority.