谁
谁 belongs to HSK 1 vocabulary. It is an interrogative pronoun.
Pronunciation:Pinyin (pīnyīn) shéi, shuí
Definition: 谁 means who
你是谁?
Who are you?
我是汉语老师。
I am Chinese teacher.
Literature
Chinese Standard Course HSK 1, Lesson 4.1, p. 22/23/24