traitor

n. 叛徒,卖国贼

He was surprised to discover that his best friend had turned traitor.

他惊讶地发现他最好的朋友竟成了叛徒。

The angry crowd shouted,"Knock the traitor on the head. He is not fit to live."

愤怒的群众嚷道，“杀掉这个卖国贼，他该死。